Just because the Inca have a Hills start bias, in the games I've played I've very rarely had a start where my capital could actually use Terrace Farms to any degree of efficiency. Yes, sure, you can build 'em on every hill, but a Terrace Farm on a hill with no mountain next to it nets a total of 2 food and 2 hammers, or three if it's next to a river post-Civil Service. That's okay, but doing that sacrifices between 1 and 2 Production. Even with two mountains next to the hill, you're getting 5 food 2 hammers (and you'll often have to wait to the Industrial Era with Fertilizer to get up to even that yield.) 9 times of 10, you'll have to wait until your second and/or third cities to efficiently utilize the Incan UI.
The Polders on the other hand start off in the same boat as the Terrace Farm. Yes, it's pretty rare to have a start where the Dutch can immediately take advantage of their UI. But here's the deal: Maybe you have to search a tad more to find Flood Plains, but I find Marshes pretty frequently, even with a Grasslands start bias. And when you do find tiles you can build Polders on, they're usually in "clumps." And, oh yeah, since no one else wants to settle near Marshes, there's way less competition for those city locations. So once you get your city founded, you can start adding +3 food to all of those worthless tiles. Suddenly a city with, say, 3 Marsh tiles around it gets 12 food from those tiles. That's impressive
Now here's more. Yes, you have to tech Guilds to unlock the Polders - but now that that unlocks the Artist's Guild, it suddenly isn't so crappy. And yes, you have to wait until the Renaissance before you get that Production and Gold boost from the Polders, and yes, it's only 1 Production. But it's also 2 Gold, a major, major bonus in BNW now that Gold's much more rare. 5 Food 1 Production 2 Gold > 5 Food 2 Production (Gold is king.)
Also, I don't understand the argument that the Terrace Farm synergizes well with the Incan UA. Is it because you can move a Worker to a Hill and Terrace Farm it the same turn? That synergizes like the Moai and the Polynesian UA. It's not bad, but it isn't good, either.
I'm not saying the Terrace Farm is an awful improvement - it most assuredly isn't. But totally and in every respect better than Polders? Eh, I dunno...
better than a farm. Terrace Farms are better early because you can get a 3 
tile (free deer) with just two mountains after construction. CiV is all about snowballing and this early food bonus helps with that.
. I've never noticed that other Civs shun marsh-heavy areas. I'll have to look out for this more. Yes, your 3-marsh-city can get 12 food with polders. The only problem with this is that it is quite rare to get 3 marshes in your first ring and if they aren't you will have to spend a fortune to buy these tiles. Marshes are just so expensive to buy and the cultural border expansion mechanism hates them. I just checked this with IGE and yes, the expansion mechanism prefers hills over marshes.
and 2 
, but that's not all: you can enhance those values with the Sacred Path pantheon, a University, Hotels, Airports, the National Visitor's Centre and a Golden Age. With all those bonuses, your jungle tiles would net you 2 
and 12 tourism. Yes, 12 (in the city with the NVC, the others would get 6). All that in one tile. You get 3 culture (2 from improvement, 1 from pantheon), so the Hotels + Airports + NVC turn that into 6 tourism. Because you are on a golden age, your tourism is doubled, so each tile grants you 12 tourism, and that is huuuge because jungles are fairly common, so this beauty can be spammed. Also, Polynesia can also get big tourism bonuses from their Moais, but they are more situational, I guess.
