There is an associates degree in Physician Assistant in my town. Yay!
But are the Masters and Bachelors programs better? I have my Bachelors in Child Development so I can get my Masters or associates degree just as well.
Go with a masters. The program is more comprehensive and will give you a better overall education in the health care system and the PA's role in it. Also, there has been talk of requiring PAs to have masters degrees, I believe; you'll be ahead of the game. Plus, MMSc., PA-C or MHS, PA-C looks better on a labcoat. You'll also be more competitive for jobs when applying with Nurse Practitioners for the same spot (they have a bachelors or associates in RN and then do a masters, I think).
If your stats/experiences are competitive, check out *double* Masters programs (I know GWU in Washington DC has a MHS(PA) and a MPH double degree program in 3 years--and then you're like SUPER competitive for any career in health care you could ever want to pursue. This is especially great if you're young and willing to devote the time/money now to be more prepared and better qualified later.