3M belts are great. Don't forget to try the Trizac versions for finishing.
Regal ceramics also are great as are Nortons in the bigger grits, ie 36, 60, 120. Hog out with either of these. I haven't tried Regal in smaller grits but have in the Nortons and found I have a *slight* bias for 3M.
The more expensive belts last much longer than the cheaper belts, even the '2 for price of 1'. They tend to track much better and the butt joint seam is less of a problem when using smaller grits (120 and smaller). I have found it is cheaper in the long run to use the best quality belts.
Most importantly for me, I can get a significantly better grind line using a better quality belt.