Darvond: SaGa 3 I was expecting the same random number, random meat, random plot revelation nonsense that the previous two games had, and I had interest in Legend of the Holy Sword (SD1). So it turns out maybe putting an action RPG on the Game Boy has some issues, but SaGa 3 with actual level ups and a sensible progression system, plus the ability to make your entire team into killer robots was pretty awesome.
I actually, for yeals, felt that SaGa 3 (original, not DS) just didn't have the depth that the previous games had, and while I still think that's true, having learned more about the game, I get to see more strategic depth that I used to. With that said, random battles are a bit uninteresting, especially later when you can one hit kill most enemies with petrification, or win battles with two all-enemy-target spells.
With that said, I think the progression system of SaGa 3 isn't as interesting as that of SaGa 2; on the other hand, SaGa 2's growth system, for humans and espers, is just too slow. (If you want to beet the game fairly quickly, the best parties to use are those containing only robots and monsters, since they don't suffer from slow growth.)
Incidentally, SaGa 3 did get a (Japan-only) DS remake that got rid of XP and instead used a system where attributes grow by actions and where weapon and magic skills level up by use. I found that remake to be enjoyable, with the exception of the way encounters were handled; I would consider it to be worse than the original, actually. (Visible enemies that move in real time, and late game they move faster than you, so you can't avoid combat without stopping time.) It's also worth noting that, unlike in the original, in the remake you can eventually reach the point of wiping out entire endgame enemy parties with one spell (instead of needing two), even on hard mode.