We primarily considered Telerik and Syncfusion, a few years back. At that time, we felt that Telerik was more understandable and easier to use, but we ended up going with Syncfusion for two reasons - they had several controls that were critical for us that Telerik did not implement at the time, and the Syncfusion ListView simply performed better.
Our choice has had mixed results... probably that would happen with any large set of controls. I often wonder what it would have been like had we selected Telerik instead.
Someone else mentioned the SF PDFViewer - that has generally worked well for us, however it does not support free text callouts and annotations properly. We have had an outstanding feature request on that for about a year, and nothing has been done.