I would recommend to stick with the FM15 untill the FM17 will release.
I won't recommend FM16 (in general).
I didn't liked the part when i bought a game (in fm15 the real names was there) and i was surprised that the Brazilian clubs names wasn't real, and for it to be real you need to download some files and put them in a specific directory to make it work (which is a lifesaver, I'm greatfull and thankful for the people who took part of it in order to let us enjoy the game as we like).
there is a thing with the crosses this year which is extremely makes the game unrealistic, a full back can end with more assists thans any attacker in game, which is completely unrealistic.
There are many nice features aswell, but as i said, in general, stick with the fm15 untill 17 is out.
the fact that the game is harder it makes it more challenging, that's might be the only reason i would consider buying this game.
of-curse that's my perspective only, other people might think way much different.