Somewhat of a dissenting voice, but I think AOT is fine. 1200 baht for a Camary (or equivalent). Counters right by baggage claim, they walk you right to your car. Never have to worry about booking ahead of time. Drivers have always been reliable, cars have been nice, etc. If you book your return with them at the same time, you get a 25% discount (i know someone mentioned in another thread that this was no longer valid, but it was available last month).
yes, you can find slightly cheaper limo rides or even cheaper taxi. Just for the convenience factor, AOT is worth it for me. Depends upon your price threshhold tolerance.