It depends on how much of a "web guy" you are. When I was contracting, I did some evaluation, and found that devexpress aspXperience was way beyond the competition when it came to things like animations and behavior. They also offer a great javascript API that is well documented and fully featured.
At work we use telerik, and while most asp guys love it, I hate it. Their controls are very good for people who transition to the web from the winforms world, but for web guys they tend to be frustrating to work with, and typically look and behave like what people were doing outside of the asp world 5-10 years ago.
I would recommend doing your own evaluation. If you hate working with javascript, you will probably love telerik. If you think javascript is awesome, devexpress is probably for you.