I posted my comments to a similar question MrBob had earlier in the US PSP launch thread:
I've played through RtA and I've got a lvl 18 Druid in Untold Legends at the moment. Short answer to your question - I'm liking the single-player in Untold Legends over the SP in RtA.
If you played Champions of Norrath, the single player experience is largely the same in RtA. Many environment tilesets and creature skins are reused in RtA from CoN and some of the new ones are uninspired. New to the game structure are side challenges that range from arena combat to standard level runs with slightly different objectives/parameters than main quest levels. The main quest itself can be played from a good or evil perspective which changes very little. Like the "save the kitties" level in CoN, Snowblind has decided to include even more diversions from the standard dungeon hack formula that simply don't fit - like a "stealth" level and a "block push" level where the game clearly makes no control accomodations for either
Beyond that, it's still delivers the best feel for straight dungeon hack combat right now on consoles, but that hasn't evolved much from Snowblind's initial offering with BGDA.
I'd have to say I like Untold Legends better right now, if only because the Everquest setting has proven to be a little too generic and the original fantasy setting that SOE has crafted for UL, while by no means anything other than derivative, is still better realized I don't disagree with shpankey that the story could be considered average, but it's a hell of a lot better story and better delivered than what's on offer in RtA, even if it done completely through text. Beyond that UL is otherwise a very competent dungeon hack that handles the combat well, offers plenty of looting, has a decent art style with generally well-rendered environments and fairly diverse creature variety so far. Downsides are the load times and bit too much re-use of the same areas/dungeons for new objectives.