I think all of the biggest names are "the best."

I know, not all that helpful. (It also depends on what you mean by "function" - orgasmic capability or depth. The Thai surgeons are legendary for offering amazing depth, more than most of the others can manage, whereas pretty much all of the good surgeons will do their absolute best to spare the nerves and allow for orgasm.)
I went to Brassard; I got adequate but not excellent depth (5.5"), complete sensitivity and orgasmic capability, and looks good enough that a gynecologist and a bunch of ER doctors couldn't tell. That reflects my priorities - I'm in a lesbian relationship, so depth wasn't a big concern for me, but being fully sensate and as close to cis in appearance as possible, was.