I think it was Fifa 15 on last gen was just to placate the people who hadn't upgraded yet. Now, I had Fifa 14 on Xbox One, so I certainly had 15 on it as well and can't really comment.
As far as PES 15, the little I played of it it was not favorable to Fifa 15 and the Ultimate Team component had no market place (so, I would never get the players I actually want, because I have no loot luck whatsoever in any game). It also looked terrible. Look at the Cristiano Ronaldo videos on youtube. He has a badonkadonk.
Fifa does need to revamp the single player portions. The create a player is terrible and you max out at like 92 anyway, which is stupid. In the other EA games (at least, in Madden), you upgrade stats based on currency earned through performance. In one season as a RB, I went from like 70 to 85 or so. They also give you things like "force starter" option that is missing from Fifa. If I am able to pick which team I am to be on, sitting on the bench for 5 seasons just wastes my time in even playing.
I think FUT will be pretty good in Fifa 16 though. The changes EA has made were terrible for the already ridiculously broken market in Fifa 15, but going forward in a fresh system, it will be good.