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.