Both games have there issues, I'm more of a tactical type of person with formations, what I love about pes, it has player types, box to box, anchor, enforcer,type midfielders for example, whereas FIFA doesn't have that or I can't find it if it's there. Straight out of the box pes is absolute crap, with the right OF it is awesome cos it sorts out all the teams formations and tactics, but I agree needs a patch to fix the underlying issues the game currently has running down the wings no fouls,
Fifa is great but lacks that formation creativity and also noticed in the demo game tends to speed up at times when you have a shot, has been a Fifa issue for years and also a massive turn off with FIFA is the headers there most of the time power headers don't look right, all depends what your after both good games IMO.