I voted Chrono Cross, just because I 'like' the story better.
Maybe that 's so called 'first impressions are most lasting', I don't mean Trigger is worse than Cross.
I played Radical Dreamers first, before I even knew the story of Chrono Cross or Chrono Trigger(don't say I'm from Mars...)
Then I felt it was interesting, so I made a Chinese translation patch. That's when I wanted to read the story of this series, but I didn't until the translation was almost done because I didn't want to be influenced.
Then I began to read the story of Chrono Cross, and articles of this site...
BTW, I didn't know there're dual or triple techs in Chrono Corss before I read a walkthrough. It has more than 40 playable characters, maybe it's hard to pick 2 characters who happen to have dual techs by chance...