Some of the good but affordable hotels are
- Hotel d'Angleterre
- Hotel Medieval
- Hote Danieli
- Hotel Regina
There are also better but more expensive hotels
- Hotel Cloitre Saint Louis
- Hotel Mercure
- Hotel Mirande
etc...
You can find them, and many others, on Booking.com.
We do not recommend hotels outside the walls of Avignon especially because of transportation difficulties.