6 of one, half-dozen of the other really..

Sound on the PSOne release is *worse* then the FF2 on the SNES but, has a difficulty gauge to it plus those extra FMVs ~ abilities/spells that were removed from FF2 due to censoring. Loading times between the two isn't really a issue but you might be more secure going the PSOne for the Memory Cards - though I may be wrong, never had a SNES as a lad so I cant really vouch for its ability to maintain save files.

Good luck finding a copy of either though, outside of eBay you'll have to lurk retro shops / garage sales and hope to be the first on the scene.