I use Telerik Reporting because it comes with the Rad Controls suite I already subscribe to. That said, if you have any use for other ASP.NET, WinForms or WPF/Silverlight control suites, then getting Telerik Reports as part of a bundle is an absolute steal.
Compared to Crystal reports it is far easier to configure and use although a bit more simple. That said, I haven't run into a scenario yet that it didn't provide for. One major caveat though, it uses Visual Studio 2005 or 2008 as the design studio, so if you are using Express or not using VS at all, you are out of luck.
I have trouble recommending Crystal Reports anymore, unless you have in house knowledge of Crystal Reports already or you intend to offload reporting tasks to a non-developer position. Even then, I think Crystal Reports has become overly complicated for most secretarial type positions to get by. One big plus in CR's favor though, is the wealth of resources available.