Interested in Ken Rad or Sylvania VT231. Which sounds better? Currently using Sylvania 6SN7W in my ModWright 5400...
Wig 
Don't know as I've never tried any of them. They were part of my tube buying spree for possible future gear. I'm divesting most of my tubes as I don't expect to change things for a long time.
This is how Paul Lindemann described them on the boxes:
Sylvania - Natural bass with extension and bloom. Amazing midrange with liquid clarity and a natural tone. Sophisticated and extended highs. Medium warmth.
RCA - Strong bass with natural bloom. Midrange is very liquid, lush, natural tonality and musical presentation. Highs are sweet, not too extended, but beautiful. Good dynamics, slam, stage and inner details. Very warm, lush sounding tube.
He didn't describe the Ken Rad.
There is now a link above to pictures.