Osters are excellent clippers. So is Andis. It depends on the model, some are better than others. I have this one & love it:
Amazon.com: Andis 22360 AGC Super 2-Speed...
You need to buy separate blades for the above model. It comes w/#10 blade which is to clip sanitary areas, under paw pads & cut through mats that are to the skin. Can be used under combs but the #30 is best for that.
Depending on how short or long you like their hair, you can get #7FC, #5FC or #4FC for the body. For blades, remember: the higher the #, the shorter the cut. I like the 7FC for soft cottony hair, gives a smooth finished cut w/out looking 'shaved' (if you use #10, they will look shaved & might need sunscreen when going out in the sun & can get clipper burn), 5FC is good too, leaves more hair on the body. For silky hair, I like the 4FC or 5FC in the hotter months.
Amazon has reviews of most of the pet clippers.