There isn't one 'most powerful' really, in that bite / hold / set up / environmental conditions all come into play.
Saints, BB7s, Hope Mono Trials are all good enough for trials. 160 / 180 rotor for mods, 180 / 200 for stock.
Can't go too far wrong with any of them, try one and see how you like it. Between those 3 they each have their plusses and minuses.