it's not about userbases, FF13 could easily sell on par with other final fantasy games despite being on a much smaller userbase, FFX already proved it anyway. A series as popular as FF does not depend on userbase.
DQ wins for sure, even if it was DQ on PS3 and FF on DS, i would still choose DQ, although it would be close.
currently playing: Skyward Sword, Mario Sunshine, Xenoblade Chronicles X