awalterj: Both are must-have games so it comes down to the order in which you want to play them.
I strongly recommend starting with FF6 because Chrono Trigger has a much more interesting battle system with double and triple combo attacks involving multiple characters and there are no random encounters so it's more sensible to progress from FF6 to Chrono Trigger than vice versa.
Chrono Trigger is a bit meh at the beginning and then gets better and better, FF6 on the other hand is captivating right off the bat. I already felt fully immersed during the intro. In terms of story and atmosphere, I give FF6 the overall edge. Chrono Trigger has more humor but FF6 had a more cohesive storyline, at the cost of player freedom but it increases immersion so it's a trade-off. FF6 also has a much more interesting villain who is certified insane. Characters are memorable in both games and Chrono Trigger has my personal favorite one (Frog), overall the character stories are more mature and believable in FF6, surprisingly so for a fantasy game with cartoony cabbage head pixelated characters.
Both games have very nice tilesets and sprites with Chrono Trigger winning in the graphics department. Music is of equal top quality in both games. Definitely don't miss out on either one but for aforementioned reasons I'd say start with FF6.
FF6 is captivating at the start but gets more meh the later you get.