Having played both games demos, i felt the PES2010 demo better. But comparisons right now would be meaningless since we haven't played the full games anyway. Saying that one or the other is better (full game-wise) is illogical at best.
Myself, i'll get PES2010 because i can't get into the gameplay of FIFA, but that's just personal preference and not because i dislike FIFA, hell, i even play it once in a while with a couple of friends ;)
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
