I've tried Ruby EL34, Winged C EL34, JJ KT77, and 5881 in my VH4S. For modern metal and the clean tones, the 5881s (or 6L6s) are definitely the best. My amp tech and my brother (both guitar players) agree with my conclusion that 6L6s sound best in the VH4 for modern and metal tones.
EL34 type...