I'm not sold on the league mechanic yet, but I'll just have to see how it plays out at launch as they are always pretty hard to gauge from the trailers. Some of the changes do look pretty interesting, rare monsters, harvest, beyond etc.
A lot of the uniques seem a bit more useful too, levelling should be even easier now as some of them are now bonkers at low level.
The removal of the mana reservation stuff is a bit of a kick in the nuts, seems very counter intuitive to why they changed the whole system around that previously?
The Divine/Exalt changes are hard to gauge as well, I'll probably just rely on good old chaos farming for the beginning to see how things pan out.
I've no idea what I'm going to play at launch, nor what I'm going to pick on the atlas tree.