I'm unaware if breed matters in trick riding, but I'm sure it should be something hardy. I was told by an ex-barrel racer that light-colored tack looks good on darker horses, and dark-colored tack looks good on lighter horses, if that would help.
One thing I have noticed is that Mustangs are weaseling their way into the trick riding world. There was a group of girls I saw that had only Mustangs in their "squad." But I can imagine that any breed can excel in the sport.
Personally, I would go for a darker horse that isn't "too dark," like black or dark bay. Too much contrast with your tack can cause diverted attention in your audience, which isn't what you want.
BUT, is your tack solid white or white-accented? I found
this image where a dark (I can't tell very well but I'm guessing seal brown or dark bay?) has white-accented tack (namely in the saddle and breast collar), and I think the horse looks rather "handsome."
In the end it's entirely up to you; I took the ex-barrel racer friend's advice and, hence far, it hasn't disappointed me.