Alot of great 6SN7 types out there!
To my ears the Ken Rad - although a great tube with the best bass, has the weakest midrange and treble. The Metal based Sylvania sounds amazing for the first couple hundred hours, but the pixie dust wears off as the tube starts to age. The Raytheon flat plates are fast, dynamic, clean and exciting - but lack any midrange texture and warmth. The RCA VT231 and 5962 both have the warmth in the mids, but are not as transparent.
The best tube overall, in a neutral system is the VT231 Sylvania. Bass establishes a great foundation for the music, midrange is the best I have ever heard from a 6SN7 type, and the treble is clean and extended.