There are different family's and types...
This is a quick "generalisation", and a combination of my opinion after trying a lot of them, and the written consensus.
6AS7-family (ST-bottle/"Coke" bottle):
Good "normal priced" tube: RCA Black Plates 6AS7(g)
"Best" expensive tube: GEC CV2523 (6AS7G)
6080-family (Smaller bottle)
Normal-priced.. buttloads. Sylvania 6080, those RCA 6080 you showed etc...
Expensive tubes: "Bendix" 6080WB
5998-family (ST-bottle) ("higher gain"):
Chatham Electronics/IBM/Tung Sol (all the same, made by Tung Sol) can be called either 2399 / 5998; Western Electric 421A is also made by Tung Sol, but the WE421A are a higher grade, although this is debated
5998A-family (Smaller bottle) ("higher gain"):
5998A and 7236 are said to be pretty much the same. The 7236 is a computer-rated 5998A. A bit faster than the 2339/5998, but worth a try
Edited by ValentinHogea - 1/5/13 at 10:01am