Back to easy mode topic:
1.) Spain: honestly I started making this post three times already and it keeps turning into a novel, so I'll try to make it somewhat abridged. CAVEAT: start on a continent split, which they have a start bias towards, with the capital placed on a small, small "continent" bearing in mind the difference in civ terminology between "continent" and "landmass" BONUSES(3) trade routes, builder/districts, and missions. SUMMARY: with the capital starting on a small "continent" every other city (except perhaps the first expansion) will be able to take full advantage of all of these bonuses. With TRs, forget that if they're on the same continent they get 1H/2Fth/3G because as long as the 2nd (or 3rd) city is on a different continent, every TR will have an off-continent target and get the full 3prod/6faith/9gold. The basic strategy is to get as much prod as possible, with the incredibly strong tangential effects of continuing to sprinkle on in heavy increments FthPT and GPT purchasing power. Additionally, while the capital still probably makes HS first as Spain does well with a religion, you put a high emphasis on getting the government plaza (with ancestral hall, more on that later) and diplomatic quarter. Just with that, as soon as you plunk down a new city (on a different continent than the capital) send a TR to the capital for 3F/6P to get it from infancy to productive incredibly quickly. Then add in the 4 production districts and the trade route becomes 3F/10P, with more food from additional districts to come. Yeah, Spain does well with internal TRs, the usual downside to internal TRs is that you're sacrificing one of the most potent GPT sources in the game, but as all your TRs will make 9 GPT, that's more than covered. Not saying that Spain shouldn't use external TR, just that they have an option to get new cities started in hyperdrive. As if that wasn't enough to get new cities booming quickly, every city other than the capital gets +25% to building all districts; that's 10% more than the centerpiece bonus of Egypt and 5% more than the Nubian bonus (unless there's an adjacent pyramid, but how many cities have that?) and the TR hammers get that multiplier, and all while sprinkling in heavy doses of GPT and FthPT AND every new city will get a free builder (or two if you have the ancestral hall - remember earlier about gov and diplo quarter.) And finally there's the missions, which I'm surprised get the lukewarm reception that they do. (Again, with the continental caveat...) every one is +1F/+1P which makes them all some of the most useful tiles to work outside of resource tiles; 3F/1P and 2F/2P are great tiles for the city, and an extra hammer when there's hills. That's for the city, for the empire every one of them makes 4 FthPT, and when in conjunction with the TR makes Spain's FthPT have two very potent sources even before considering holy sites. And that +1 BPT doesn't seem like much, but on a tile that helps the city so much with food/production and the empire so much with faith, you can nickel and dime your way to quite potent science output. I like to forego holy site and campus adjacency altogether and try to have both districts surrounded by 6 missions - the 12 BPT you'll make from working those tiles is at least equal to, usually better than the campus adjacency, and the 48 FthPT is more than the HS adjacency. And once you hit the late game civic that adds 2 beakers to every mission... it's just game over at that point. And the early fleets/armadas and conquistadors are good bonuses that in the context of Spain, are just gravy. Everything just blends together so that, while many civs can get one or two, maybe three yields really high through their bonuses, Spain has good a.)food from mission tiles and increased reason to use internal TR, b.)production from trade routes, missions, and district bonuses, c.)gold - a bit more from trade routes, d.) science from missions and later A LOT from missions, and e.) faith - their strongest yield bonus, heavily from missions and a nice bonus from TRs as well. This argument is often countered by "yeah, well with the Khmer, all my holy sites are getting 10 hammers and faith" and I agree the Khmer are very strong (and digress that there's a ton more to speak of in this comparison, but again, look at the length of this post already) but I just feel that Spain has more bonuses from more sources affecting more yields and is easier to implement (again, when starting with your capital on a small continent and a split.) And yes, that was the abridged version!
2.) Mali - probably a controversial pick as they have one of the most crippling penalties which most heavily impacts the most crucial part of the game, the start. But once you get things rolling, the snowball accelerates a lot faster than most other civs. When I get them with a start position which is simultaneously the best start for their bonuses and the most difficult start for all civs, all-out desert,I always go for the Reeds/Marshes + Etemenanki combo - the extra production helps to compensate for their starting handicap and the beakers are not only a great source of science throughout the game, but help you reach that point in which your strengths start to make up for your weaknesses- Currency and the Seguba. I like to try to get one city that has every single tile (or as many as possible) desert, and send out all trade routes from that city. Even more potent with Great Zimbabwe and can be a next-level city with Petra. I'm not so sure about the trade off with mines, even though he can do great things with gold purchasing- lumber mills don't lose the production and later on their prerequisite terrain be planted. I do have to say that for a civ that has gold- and faith- purchasing power amplified at the expense of production, his gold-generating bonuses are on point but the faith-generating bonuses are a little lackluster. And you could argue that Portugal has stronger gold generating bonuses and with Mali's underwhelming faith generating bonuses that makes them simply better considering the production penalty... and I'd agree with you, Portugal is outright better. They're just more of an obvious choice for easy mode so I left them out.
And for the final two, I'll cover two of the possibly forgotten civs as NFP has turned nearly every facet of the game upside-down, but these two civs are easy mode for reasons before NFP, weren't really affected by it (eh...), and still hold true today:
3.) Nubia - map type doesn't really matter, maybe just an emphasis on having a close-by neighbor. The archer rush is always a great way to kick-start any game, and Nubia does it better than anyone. It's kind of laughable that the unique archer is "more expensive" than a standard archer because the cost is decreased due to one of Nubia's other bonuses, making them cheaper. So they're cheaper, faster, stronger, and gain promotions faster. They can archer rush better than anyone (yes, I hear you Byzantium fans) but it does create a bit of an urgency as the archer rush window pretty much ends when the targets have walls. But that's where Nubia's archers getting promotions faster can make a big difference - once they get incendiaries and the extra shot from expert marksmen, they may be able to keep moving forward. That's how they get things started, the district bonus helps to keep the momentum going. And some extra yields from mines is always welcome.
And the thing about a civ like Nubia, who can hit the ground running, take over a nearby neighbor or two for both more cities and more territory to make even more cities, and then has decent bonuses to improve all those cities faster, is that you can then win any way you want. Continue the aggression and win by Dom, get a campus in all of them and win space, get a theater in all of them and make local optimizations for culture, or focus on faith and win religious. Very versatile, pick-your-win. But a civ that does this even better than Nubia IMO is...
4.)...Persia - while Nubia is good at what they do, they don't have any combat bonuses aside from the stronger archer (and its promotions) Persia also has an early game unique unit who can attack with impunity, is a little more rugged so may survive a walled city siege, and the civ has a +10 combat bonus for a limited time after declaring in the only manner that they would declare as it's the easiest and the penalty for doing so is reduced. They also get a little bonus in getting the cities online as their yields aren't diminished from being occupied and a not-so-little bonus of retaining the city with the loyalty bonus. From an early game infrastructure standpoint, one extra TR early is double the number that you'll have for an extended period of time, and the bonus to domestic TR is eh... not unnoticeable, not sure if this gives them enough incentive to prioritize internal TR, but like Spain but to a lesser degree, having all cities send a TR to a city with gov and diplo districts and then the 4 TR hammer districts is a viable option and the downfall of not getting gold from your TR is somewhat mitigated by their bonus. The unique improvement is another way to supplement your GPT if you decide to go internal TR, but I wouldn't go spamming them like missions as described above or, for example, outback stations, as they don't help with food or, more importantly, production. At least not yet. So like Nubia, they can hit the ground running, and then have some infrastructure bonuses to help you get the V when you use your early snowballing to allow you to win in any way you want. But the difference is the late game option offered by the pairidaeza - if you've been planning for what you can do in the late game, which means less mines and more lumbermills, positioning of the pairidaeza, as well as possibly going with earth goddess (which is immensely helpful early as well), then you can just national park all over the place, funded in part by Earth Goddess, and have tons of seaside resorts, your late-game tourism can become so potent that you can divert to the tourism win if somehow things go sideways, and easily finish the deal if that's what was intended.