High gain metal: Russian 6P14P-EV, no questions.
I went down that rabbit hole. Basically, you want the EL84's that sound the least like EL84's. You want the widest EQ range, the highest headroom, the cleanest and most powerful. Those are it. Because even those have a much narrower soundstage than any big-bottle and even 6V6's.
If you don't want to risk getting NOS, the current variations/tweaks are your best bet, IMO. Sovtek EL84M's, Gold Lion N709's, Tung Sol 7189's are all variations on the old Russian 6P14P-EV.
There are some sites that state that the TAD EL84's are the most 6V6-like... I don't quite agree. They do seem to have a sparkly top end (compared to other 84's), and a scooped low midrange (for clarity), but 6P14P-EV's have more girth.
Keep in mind, though, even the best EL84's still sound like EL84's, and I still don't think any pair of them is gig-worthy in a Metal scenario. But they work great for recording as long as you keep the poweramp loud enough to work its magic, but not super loud so that the EL84 sound starts to kick in so blatantly.