I use an Andis, and so does everyone at the shop i go to school at. i have these clippers.
PetEdge: Andis UltraEdge 2-Speed Clipper and
PetEdge: Andis AGC 2-Speed Clipper The first clipper is faster and is what i use as my main clipper. The second clipper is the one i got in my tool kit for school. both are good clippers.
I have used some whal clippers. these ones
PetEdge: Wahl KM2 Professional 2-Speed Clipper i used at a few animal hospitals. They were finicky after a lot of use. But they also weren't taken care of as best as they should have and they were dropped some times so that may be why. This clipper
PetEdge: Wahl Bravura Cord/Cordless Clipper Kit is awesome on cats. I use it to do lion cuts (and i'll have 3 to do tomorrow...yay...lol)
And these are the various combs i use
PetEdge: Wahl Stainless Steel Attachment Guide Combs Set metal ones are best. the plastic ones can pop off and then you have a nice chunk missing from the coat you were clipping.