I've not played much of V, I heard the GBA port was a good version though (the GBA version of VI is probably the best).

As for PS2 era, that is where I found things started getting a little rough, I enjoyed X at the time, yet am worried about going back to it, and X-2 was a bit of a shark jumper.. XI was online only so ner.. XII was a big big change for the series, and the story isn't that great, but it does at least change things up with new (at the time) ideas. And its pretttyyyy.
For me the PS2 era is when RPGs started getting weighed down by their own systems, and beyond the most accessible games (Dark Chronicle, Persona 3/4), none really stuck with me. you might click with a few odd ones though, Valkyrie Profile 2 comes to mind, Star Ocean 3, Xenosaga (I think?), Lots of odd Atlus games like Digital Devil Saga 1 and 2.. but yeah.. systems, grinding, not enough time...