Hi, Personally I prefer the JJs. In class A amps (like all my designs) they have a solid and clean bass with good mids and nice extension on the top end. They are also really consistent and stay "biased" over a long time. I use them at about 35-36 watts dissipation (each tube A+S). For a seemingly "crisper" sound the JJ EL34s are great at about 25 watts (A+S) dissipation. But my go to now in the amps are TS KT120s running at 25 watts dissipation (A+S) into 8K load. Magical IMO. Obviously class A U/L P-P is not efficient. A good source of heat in the winter though.