I have experience with all three, and in my opinion Telerik offers the superior product for ASP.NET development. Each suite has a devoted fanbase, but Telerik's suite just seems more intuitive. Their controls are just easy to use and they work well. Their support/community and documentation are fantastic too, which is a big plus as well.
If I had to rank them:
- Telerik
- DevExpress
- Infragistics
I've had good experiences with both Telerik and DevExpress, but I found Infragistics a little too bulky and convoluted, and it seems like you need a lot of hacks to get their controls working correctly with the more out-of-the-norm implementations.
Maybe it's just me, but it seems like Telerik is slightly more concscious of best practices than the other two, especially Infragistics. Both DevX and Telerik perform well with a lot of data, but DevX might have a small advantage there. When it comes to aesthetics though, Telerik wins hands down. Looking at performance and aesthetics, I have to give it to Telerik.
I think you'll be happy with either Telerik or DevExpress, but you'll have to weight them for yourself. I would pick Telerik, but that's just me.
Resources
If you're willing to take Infragistics off the list (which I think you should), here is the best comparison that I could find, and it's probably not as detailed as you were looking for:
Here is a fairly detailed comparison between DevExpress and Infragistics (and some other suite):
And here's another question on SO, but it has some good information from a lot of users: