They were all great. I enjoyed GoW2 a bit more than the first one since I sucked at the QTEs in the first game (still had to look at the controller where the triangle and square were lol) I had to repeat some boss fights way too many times.
Story, environment wise they just kept getting better. I miss the behind the scenes stuff you got with the old games on disc. Hopefully Ragnarok will include some concept art at least. I think it was GoW2 which had a bunch of development videos on disc. Yep disc 2 had the making of documentary.