I think Gears is better, I liked the combat better (I never found it any more boring or repetitive than any other rpg) and I thought the story was better.

Xenosaga was a mixed bag because it was so inconsistent throughout in terms of presentation and battle systems. They should have just made the whole series in 1 style instead of trying to reinvent themselves every game. I also despise Episode 2 because I thought everything about the game was just bad. Also, Shion was a terrible main character.

Xenoblade is a fine game but I felt the combat was a bit boring.

That said, Xenosaga and Gears could have greatly benefited from better dialog/writing/translation. I played Xenosaga Episode 3 again last year and I was cringing left and right at the words I heard being spewed forth. As Harrison Ford told Lucas, "You can type this trout, but you sure as hell can't say it." Gears fairs far better because it is never said but there is still plenty to clean up.