Bannor, Lunan, Hippus, Doviello, Malakim, Sidar, Clan of Embers, Calabim, Balseraphs, Amurites, Grigori, and Elohim have access to most the core units that make up the game (or their analogs). If you select one of those groups you wouldn’t be scratching your head trying to figure out how to attack a city without catapults (as you would with elves) or why you can’t obtain mages (Khazad). In addition, most of their unique advantages are either intuitive or can be ignore without significant plenty.
Of the ones listed above, the Clan and Doviello cannot build libraries and are barbarians. This can result in a significant research hit making it difficult to catch up if you lag behind. Doviello does not require buildings to construct units, which is nice but it isn’t a great way to learn the game as other civs do require these buildings. The Clan’s axmen can’t be upgraded to ogres, which means your high-level axmen will always be axmen, but that isn’t really a huge deal as you’ll have enough ogres to more than make up for the loss.
The Grigori are great, but to obtain adventurers you need to closely watch your great person points. This can be a pain in the ass as you may need to deny yourself wonders or specialists to keep your GPP pools clean for adventurers. Plus the buildings that issue adventurer GPPs come a wee bit late in the game. If you pollute your GPP pools with too many specialists you’ll miss out on the adventurers and the Grigori go from pretty cool to pretty lame. Grigori are also agnostic, which some might tell you is an asset for the player still learning the mod, but I disagree. You can ignore religions with any civ (except the Sheaim) just as easily as you can with the Grigori.
Calabim and Lunan both have unique champion (mid-late game melee units) analogs that require a bit more finesse to use and require unique buildings to build. The Calabim vampire requires Feudalism whereas most civs need Iron Working for their champions. The Lunan boarding parties require a sea haven to build, which means they can only be built in coastal cities and that can be a pain sometimes. Either civ is probably okay to learn at though.
The Elohim can build unique buildings in captured cities, which makes them kind of a cool way to experience many unique units and such while playing one civ. Watch out for their higher war weariness though.
Tips for the FFH2 Beginner:
Cultivate your high level units: Promotions in FFH2 are much more powerful than in vanilla Civ IV. The combat tree, for example, is twice as strong as the vanilla version. In addition, upgrade units do not receive an experience hit as they do in Civ IV. This means that you may be better off sacrificing units with less experience in order to weaken defenders for your high level units.
Good spells: Every spell has a use, but a few of them are pretty damn good. Haste and Enchant Weapon are the first level spells requiring Body and Enchantment mana, respectively, and are both quite nice.
When cast, Haste instantly gives all living units in the same tile one extra movement. This is totally awesome. Keep in mind that the spells gives one movement when you cast it, so if your army is moving through hilly terrain, move your units on the hill, cast haste, and you can then move them again. Keep in mind that this only affects living units, so siege weapons, summoned units, and demons do not receive the benefit.
Enchant Weapon gives a permanent +20% boost to all melee units in the same square. A very nice “fire and forget” spell.
Rust, which requires Entropy mana and debuffs nearby melee enemies, is also nice.