Dreamcast would be one of the worst game platforms ever for RPGs, but as pointed out before, Skies of Arcadia and Grandia II are seriously some of the best in the industry. Absolutely fantastic games.
For more action oriented RPGs, there is of course Phantasy Star Online, which if you want to play online you should just get the PC version with way more content. Star Platinum pointed out Record of Lodoss War which is hard as shit, but very cool with a great old-school "Western RPG" vibe to it, and there is also Elemental Gimmick Gear, which is kiiind of like Zelda that a lot of people like, but I could not get into it.
Evolution and Time Stalkers completely suck though, I would just give up on them sooner than later honestly.