I have used and continue to use most of the ones from your list of suites.  Here's my 2 cents:

Telerik -- I have a love/hate relationship with their products.  They are really cool right up to a certain point and then you hit a brick wall and it is pulling teeth trying to get it to do what you want.  However, it has actually been 2 years since I've used their products so I'm sure that left a lot of room for major improvement.  I have recently been thinking about downloading a demo of their latest suite and seeing what it can do for me and some new project requirements I have.  From what I remember (has been 2 years, remember) their documentation was pretty decent and their support was as well.

ComponentArt -- great suite, good looking tools, has some minor issues depending on what you are trying to get out of it.  I'm not too fond of the way you build the grid control, seems like a lot of extra fluff to get it to display your columns and allow the AJAX stuff with it, but better than dropping it onto an UpdatePanel IMHO.  Like Telerik, they are principally targeting the web so they have a bit more clout in that arena.  Documentation is a little sparse and limited.  I find it hard to actually get an answer out of the documentation when I have a question and have to resort to the online demos and the forums and ultimately, most of the time, play around until I get it right.  I haven't used their charting stuff but it looks really good.

ComponentOne -- really awesome for Windows components, their web components leave much to be desired.  Frankly, that is the reason I have a subscription to ComponentArt is because I was not impressed with C1's web stuff.  I continue to update and attempt to use the C1 stuff in the web arena but always go back to using something else.  Again, their Windows components are GREAT!  On the other hand, I find all of their components to be much easier to use than ComponentArt or Telerik have been in the past and their documentation is incredible.

I am not going to put a full comparison here, but here is why I have chosen to use telerik for 4 years now, and over countless projects. 

1. Undeniably great customer service - sometimes they even write code for you
2. Regular fixes and releases
3. Smaller download sizes for the client-side files (in comparison to the others you mentioned)

I attended a code camp this spring, and one of the sessions covered all three in pretty good detail.  Although the other two indeed have some features that telerik could definitely take advantage of, telerik topped the list in at least those 3 categories.

My one point of contention now is the price.  They are priced very well for a well-funded project, and especially a company, but a freelancer or hobbyist has no chance to take advantage of any of these great tools.