Jared, you have to ask your self some questions. What do you want out of your motor? What is your budget? Are you willing to build your ski up with the package that the shop you choose recommends. If the third question is not going to be followed, then just flip a coin. You would be happy either way..
as far as the first two questions goes.
Each shop has its specialty, or niche. There are many more out there than you listed.
I have ridden motors built by all of those except Thrust Innovations. But I would not hesitate to do have Brian build me one. Why? Because he focuses only on freestyle.
I could personally go with any of them.
But, For my riding style and my use. I would go with X Scream, LPW (My current setup) or Thrust. Why? their focus is more on Freestyle. I will also go out farther and say LPW's setups or more freeride based. That is Pauls specialty. Look at how many west coast riders run his motors. Does that mean Paul cannot build a good flat water setup? Not at all. I have ridden several of his that ripped your arms off. Now, some are gonna say, why not Jetworks? Art builds one hell of a package, I have ridden several of his motors. They pull strong from Bottom all the way through Top. Hell, one of Crammits had way more power than I could ever use, very impressive. But, I feel builder has their Niche, To me, Art's is more recreation and race setup. If I was racing a SJ still, he would be the top of the list.
As far as others out there not listed.
Steve Webster - Kommander
Keith Head - Head Enterprises
Wammer - Gil, did you ride Jeff Lutkers silver ski........ That ski ran OEM 38's and hit so much harder than my 84mm Big Bore. Wammer has a great port spec for 701 motors.
Riva - Rec Riding to racing only.
ZForce - I know Tim and his work...... For SXR Limited, he would be my first choice.
Hurricane Racing - Bill Haig has been around longer than any one person active on this board or any other for that matter. He is an incredible builder, but only racers would know of him.
TLR - Damn, wish Todd still did ski's!!!!!!!!! He was good enough for Rick Roy, nuff said. My TLR cylinder is sitting in my shop as my backup.
Watcon - I know he can build a hell of a motor. For Racing, I could not have a second thought using Randy.
Judge Motorsports. You want to go really fast on a Blaster or 15F? Nuff Said.
Ultimate Watercraft/TBM - Race spec only. Would not hesitate to call.
ProTec - No experience, but again, they know their stuff. Look at MacCluggage and Tera Laho. They dominated under them.
Now, do you see a pattern?
There are plenty of good builders. But which one is best for you? Who knows, what do you want out of them.