It depends what you mean by "who has", if you mean "who sells or who can get or who carries", then I have to say Kris at AlphaAquaculture. Any clownfish dealer can work with various breeders to get some of the best clowns, but I would say Kris tops them all in picking the nicest from everyone that he deals with. Kris basically leaves everyone else in the dust.
here's where it gets really touchy as there's a lot of good breeders thoughout the world. No one breeder is the best as everyone has some really good clowns. But hands down, overall, I have to say Bali Aquarich in Indonesia breeds the best clowns and sells them all over the world. He culls mercilessly, so as to let very few defects out. Everyone breeder has defects, how many you let out determines your reputation. When it comes to perculas, Bali Aquarich has the best I've seen. When it comes to ocellaris, I feel there's some room for improvement, although he's got the patterns down, just need to improve some on body shape, heads, fins, etc. Not sure if his ocellaris are 100% or hybrids. He's also the best breeder in the world because he successfully bred large angelfishes like annularis, clarion and maze. Bali Aquarich has done with so many different species... now, that's a breeder. In best, I hope you mean overall physical conformation of the clownfish and then patterns next. So, many people on see patterns and they think that a certain clownfish is the best and it could actually have several deformities. I've shown so many people my rejects and they think they are absolutely beautiful and they don't see the physical defect at all because the patterns blind them when it comes to designer clowns.
this is personal choice. expensive is a factor of supply and demand, doesn't mean it is the best. if the supply is less than the demand, the price goes up. also fad items artificially raises demand for short periods and then quickly fades away. a good example is the platinum clownfish. when it came out and was a fad, they were $250-$300 each, the fad faded and you can find them $50 everywhere. locally, in the bay area, no one wants them, so when I get a free pair from the breeders, I donate to local reef club swap meet.