I dont know about the others, but I just confirmed my reservations with Happy Limo. I took them from what I read on different WDW boards, it seemed like they were all pretty much the same, and Happy Limo I had a $10 coupon for... Well, I am all paid and I am all set, havent used them mind you, but its $99 for our roundtrip from the airport to the Poly + a grocery stop. I noticed they are charging me $4 for tolls (and I think I read here that they dont go the toll route?) and they are charging me $20 for gratuities, now when I confirmed this the nice lady on the phone said that is correct, but if i like the service I'm encouraged to tip them when I receive service (?huh? ok, no.) {lol I do plan on saying something to dh so the driver can hear me, about how happy I am we prepaid and it included a 20% tip}
Just if you are comparing prices just thought I'd share what I have.