Handy, welcome to the DIS!
I used All Starz (aka Starz) Limo from SNA to GCH last March for our first trip. I wouldn't recommend them. They were ok, but they had issues. First, they quoted us $80 on the website. When I called to make the reservation, I was told, 'no, that's wrong, it's $90." Then they add $20 for a tip, and there's tax, etc. Total came to about $125. Also, when I asked the driver saying, "Tip is included, right?" she replied, "We get 5%, the rest is up to your discretion." So apparently the $20 "tip" doesn't really go to the driver, unless the driver was lying... who knows?

She was very nice and prompt, so I tipped her on top of what we'd already paid. Therefore it came to more like $140 total. hmmm... very different from my $80 quote.
The limo was not the one we were told we'd get. I had even asked on the phone, "ok, we're getting [this model, can't remember, but it was pictured on the website], right?" and I was told that was correct. That was not the car we got-- it was smaller. The controls for the radio and the air were unmarked, obviously jury-rigged, and weird. The part I really didn't like is that there were no seat belts on the seat facing backward, so DH and I sat there so the kids could be buckled.
We asked for champagne, and got it as part of the package, which was nice. It was a cheap bottle, but we didn't care. There was bottled water and pepsi. I was hoping for a bit more variety; also, the drinks were not very cold and there was very little ice in the ice wells. There were glasses and napkins nicely arranged, and a decanter of gin and scotch.
On the way back, the driver called me a half hour before he was supposed to pick me up. He was lost, he said, and his GPS was broken. He proceeded to tell me where he was and ask for directions! I was like, "Uh... I have no idea?!" Plus his cell phone kept cutting out and he had a thick accent, so I had a hard time understanding. Finally he hung up, and I called the company and was reassured that they were in contact with the driver, and he'd be there, and they apologized. Still, that was worrying.
Same thing on the way back-- same car, warm drinks, no ice, and there was paper detritus in the ice wells when we wanted to get some to put ice in our drinks.
OK, too much detail! But you get the idea. I think your best bet would be to call the hotel and ask for recommendations. I wish we had!