Thank you - this is really helpful!A couple additions to the list.
6SN7
RCA 5692 Red Base; you mentioned RCA but not the 5692 version.
Melz 1578
12AU7- must purchase 6SN7 to 12AU7 adapter
Telefunken G73r
1950s-1960s era Mullard ECC82
Brimar CV4003
Mullard CV4003-rare and hard to find
Combinations
A lot of users prefer Elrog ER, MO, TM with Melz 1578 drivers
WE300B with Brimar CV1988 drivers
WE300B with Melz 1578 drivers
WE300B with RCA 5692 red base drivers
WE300B with Telefunken G73r drivers
I personally like Sophia Electric 300B with Telefunken G73r, 1960s Mullard ECC82, Brimar CV4003, Brimar CV1988, and RCA 5692 red base drivers.
Now I need to hunt for the Melz 1578.
Quick Look on eBay shows some for a couple of hundred £ from Ukraine and some for over 500 from the states… I can’t figure out the reason/difference…