In my opinion it depends on the situation and environment in which the project is done. If you have just a simple, small project, then SVN is great. As already some wrote, VisualSVN integrates nicely into Visual Studio s.t. you don't have to do the checkin/checkout over the native file system.
TFS is great for version control, but even better if you really use all of it's capabilities. In my eyes it really becomes worth if you use - for instance - the work items as your integrated repository for handling customer bug reports, new feature requests and for tracking the progress of your project by managing tasks and the according estimated time, used time and remaining time indications.
What is also really interesting is to use the feature of associating work items with source code checkins. See here for more infos about that.
