> What brands
Don't worry over-much about brands.
Big brands like Cunningham/RCA made tubes for 50 years in dozens of factories, through war and peace and changes of markets. You can't assume that they kept top-quality in every factory all the time.
Big brands always had a low-price line for radio repair with 10-day warranty, and a high-price line for military/industrial customers who logged every tube trouble and squawked about excessive failures. Because the two types were sometimes made on the same factory lines, it isn't easy to tell them apart now that you no longer get them from the factory.
There were 700-900 "common" types and no Brand actually made all types; everybody bought from other companies so that they could offer a complete list of types. If they really cared about their Brand they would try to get appropriate quality (and price!), but sometimes they had to take what they could get. All early 7591s came from Westinghouse, even though you hardly ever see one with Westinghouse's brand.
For most of tube history, the racket was all about not losing money. Most of the time there were too many factories and they had to under-cut each other's prices to keep going. 5-tube radio makers would eat poop to save a penny per radio, because radios were all the same and prices rules sales. TVs were only slightly different (with 14-20 tubes, you could not use crap tubes or your DOA rate would kill profit) but still very price-driven.
RCA thought they had a solid tube business in the 1920s, but then Cunningham out on the west coast was making a LOT of better tubes cheaper.... RCA finally had to buy Cunningham's butt (made him a VP of RCA) and his factories (which became the main RCA factories), and even then had to leave his name on the tubes. There was a similar trend in the 1950s as the Japanese shops grew big, but they were not open to a buy-out. The big US brands had to cheapen their low-price tubes to keep the factory working, and later ended up re-selling Japan tubes under their own brand.
Some "bad" brands were not all bad. "Realistic" (Radio Shack) didn't make their own tubes (they may have had shares in some asian tube plants when the tube racket was fading). Most of their tubes were lowest-bidder. But (especially when tubes were fading) sometimes the lowest bidder was a high-quality maker who had excess inventory that they could not unload. I've had some very good "Realistic" tubes, as well as some junk.
And finally: if a specific brand and construction is widely accepted as "very good", someone is making fakes. Tubes were never retail-labeled on the factory lines. Several reasons: if the workers knew what they were making, they could steal and sell them. Another reason is that the same basic tube can be sold under several tube types (and several prices) depending some on testing but a lot on how many orders you get for each type. Because there is no permanent type-tag on a tube, it is very easy for someone to rub-off the retail markings and print-on a "more desirable" marking. A lot of mediocre TV tuner tubes got re-labeled as 6DJ7 when 6DJ7 was "in". Now about any brand and type may be counterfeited onto any tube that may "work" in most sockets. Mullard and Telefunken usually -were- very-very-good tubes, but today you need to be a real geek with a strong magnifier to be sure you are getting genuine Mullard or Telefunken.
Know your dealer. An honest dealer won't sell you a bad tube, or will make-good if he's been fooled.
Try lots of "ordinary" tubes. "Sound" wasn't a design goal, and sound depends as much on the circuit conditions as the tube, so an "unknown brand" may work very well in your circuit and not in someone else's.