I've only had the opportunity to try 3 so far; Ken Rad smoked glass, Sovtek, and JJ/Tesla 2A3-40. My preference, and by a large margin, is for the latter. If you want some more info about them, then check out the
6moons review - jj/tesla 2A3-40
.
6moons review - jj/tesla 2A3-40
.