There's so many must-haves!
Here's my must-have, whittled-down to nearly nothing short list:
6SN7s:
Sylvania VT-231, 6SN7W or 6SN7WGTA, 6SN7GB (Gold Brand)
Sylvania Tall 7N7 T-Plate/racetrack bottom mica with adapter - once were cheap and plentiful - best to start searching 5 years ago.
Hytron 6SN7WGT or CBS/Hytron
Melz 1578 from 50s-60s (not cheap) - even the Melz 6N8S from the 50s is another must-have.
TungSol VT-231 Round Plate
Brimar CV1988 - clear and dark glass versions.
Fivre 6SN7GT
Toshiba 6SN7GT
Marconi B36 - best to listen to your wallet first.
Marconi Radiotron Canada 6SN7GT
Mullard ECC32 or ECC31+adapter - requires more heater current than 6SN7, 950mA
Mullard ECC33
Twins:
1940s RCA metal base VT-94/6J5GT
TungSol VT-94
Brimar 6J5G - ST bottles
Brimar 6J5GT - round plate
Brimar 6J5GT - flat plate
GEC L63 - ST bottle
Marconi/MOV L63 straight bottle - grey glass up top.
STC 6J5G - ST bottle
Sylvania 6J5G - ST bottle (also rebranded as Zenith or Silvertone)
TungSol 6C5G - ST bottle
Cossor 6C5 - ST bottle
Fivre 6C5GT - straight glass 'pasta maker' or ST bottle.
Visseaux 6J5G - ST bottle
Fivre 6J5GT
That's a decent must-have starting list with a variety of tonal options from thic to svelte to sweet and exquisite.
You can flesh it out later with VT-99s, 5692 and 6N7s once your credit card is back from detox.