Right now - and it's just based off of 3 days - I would say everything EXCEPT warfare...
However, I will say this -- I like the 1UPT/Hex system and the more strategic/chess vs. stacks of doom warfare so much that I don't think I'm in the "Civ4 was better" group... and I say this as a decidedly builder-based player NOT a warmonger.
1UPT/hex is carrying civ5 right now for me -- I dearly, dearly hope that modders and expansions will restore the missing concepts I feel are dogging 5 -- but 1UPT/hex is a real step forward.
Things I most think are missing...
Rivers seem nerfed/meaningless... +1 commerce, but that seems to be about it.... you don't need them for farms, they don't work as roads for trade routes, and with pollution gone - there's really no reason to build ON a river anymore. This seems just wrong... Look at a map of the world and you'll notice since the dawn of time - direct access to fresh water and riverways was a critical aspect of the rise of civilization. Rivers need desperately to be restored as an important part of population growth, commerce, and strategic aspects of the game.
Multi-decision tiles -- I always thought that one of the best things about IV was that non-resource tiles had a real multitude of options. This doesn't seem to be case - TP vs. farm is about it and what's more - it's not a very thoughtful decision. The decision to go cottage involved a trade-off... immediate growth (farm)/production (workshop) vs longer term commerce? I never used to automate workers... now, I don't see much reason NOT to automate them.
Wonders and buildings - I think that perhaps I'm just too used to RoM/AND - but there seem to be less of them and they seem more meaningless.