Here's a thread from these very forums about people's favorite wheels:
http://www.chiefdelphi.com/forums/sh...t=wheel+choice
As you can see, there are varying opinions on what the best wheels are, and a lot of that depends on your strategy or drivetrain. However, a good place to go for basic wheel options would be AndyMark. They sell Omnis, Traction, Plaction, Mecanum, Swerve Modules, Pneumatic, you name it!
http://www.andymark.com/Wheel-s/229.htm
It's tough to define what the best wheels are, but generally drive trains for rookies are made up of some form of traction wheels. While I'm sure 10" wheels are out there, your easiest to find COTS options will be 4", 6", and 8" simply because of the greater availability and more selection. Hope this helps!