I think this one is a no brainer. For as much as there is a RPG crowd on the 360 (i'm part of that crowd, I bought my 360 mainly for it's RPGs), it cannot compare to the RPG crowd on the PS3.
Of course, being a hugely antecipated game for both consoles, FFXIII is going to do good numbers in both as well, yet PS3 sales are going to sky-rocket over 360 sales.
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"
