Secondly, you should take a look at Telerik. Their support ranks first in the industry. They give you good examples in the real world, and their documentation, which I feel, is unparalleled.
I entered into a contract with a company rooted in the controls you control, and I would not use them if they were free.
The reasons why I make this expression is their documentation, in my opinion, is bad. When I spend money on a management kit such as RAD, it makes my work easier and faster for production. I found that in some cases it was easier to just figure out how to make inline controls, do what you want, and try to figure out the problems that I had with their controls.
Their patterns are similar to those of Microsoft. They’re fluffy, based on Tech sales, and show how easy it’s to set up something at the seminar, but in the real world, if you used the methods and tracked the viewing status and traffic with their examples, you would be less impressed.
I did not have an account to send support tickets, but I had 4 during the month sent through the account holder, and as far as I know, I did not receive a response to any of them. (This could be broken with the person I had to go through with, but I doubt it.)
When it comes to Telerik, Rad elements for Ajax, it’s very rare that I can’t understand what I need to do, or by looking at the sample web solution for the Visual Studio sample that comes with their documentation.
Good luck with your search, and even if you don't consider Telerik, I highly recommend that you look for other options.