Having tried out the 3D remake of the game on iOS, I lean more towards the old 2D sprites. There's nothing fundamentally wrong with the 3D remake, but it's going to be painfully dated years down the line, next to the relative timelessness and charm of 16-bit sprites. So in this regard, I'll probably pick the PSP version with the crisp HD sprites. It lacks the extra difficulty punch of the subsequent 3D remake versions, and the gameplay changes of the DS version, but the PSP package offers you the complete FFIV experience (even if I think The After Years is pointless).