You can't really compare the 2 TV series due to them being completely different in style and settings.
But I'll have to agree with tonymclark and say that the radio series is the best. Simply because the material was fresh and they used some gags that were never repeated on the TV version.
Also some of the songs are better than the TV version e.g Tundra rap had an extended beginning and the Mr Rodgers song had a better drum and bass to it