Big VH4 / 6L6 fan here ,
It’s odd because I much prefer EL34’s in Herbert.
A few years back I tried about every tube available that would fit in the VH4,
My favs, the JJ 6L6, Sovtek KT88, SED KT88 and JJ EL34L
Out of all them JJ’s 6L6 GT are my go to in the VH4 , big sounding tube with nice full mids for a 6L6.
Easier to get classic tones with than the KT88’s.
More versatile than the EL34’s.
6L6 is the one that does it all very well, from crystal clean, to very mean.
Sovtek 6L6wxt are also pretty nice , for a more direct thing with less overtones.