Despite not ever owning a PS1 but have owned all other iterations of the Playstation, I will have to nominate the PS2. Backwards compatibility with the PS1 alone takes this; not to mention all the (J)RPGs & tactical-RPGs released on this system, along with the backwards compatibility of the PS1 to further the JRPG/TRPGs collection.

Although PS3 & PS4 have more advance hardware the cost of not having backwards compatibility, and the general direction of RPGs towards more action-based combat leave me slightly disappointed. Of course, that is not to say all RPGs released on the later iterations are lackluster. However, I have noticed over the years I have been less enthusiastic for contemporary, original RPG releasess as opposed to the classic turn-based RPGs that seem larger in scope, and do not douse themselves in excess noise.