Which tubes are the best?

The only tubes I roll are the signal tubes and the only tubes I use for my power tubes are Genalex. I have three different amps and all of them have either the EL34, KT-66 or Kt-88 tubes

You can read what Jeff Day says about the Sofia Electric KT88 ST tubes here : https://jeffsplace.positive-feedback.com/the-sophia-electric-kt88-st-and-el34-st-vacuum-tubes-review...

Might check the provided link below. I found it to be helpful and reasonably accurate in tube gain. Like millercarbon said, it can get expensive. I was looking for more high frequency detail. I found new production Mullards to lack the dynamics I wanted. I have Bob Carver mono blocks that use KT88s. Purchased used. Previous owner had already upgraded the tubes. The KT88s were Gold Lion. The 12AX7s were some old stock Millard medical grade tubes. After rolling tubes, I ended up liking the sound of new production Gold Lions. Actually have replaced the tubes in Manley Chinook with the Gold Lions as well. The Gold Lions have more gain at higher frequencies. Hope you find what suites. Happy Listening!  
https://www.scribd.com/document/383393010/12ax7-Comparison-of-Current-Made-Tubes-2016-1

JJs are available from CE Distribution cedist.com

a few points i’d like to make here

1 - there are basically three makers (factories) of tubes today, china (shuguang and other brands, in changsha/guangdong), russia (sovtek and related brands bearing many old names, in saratov, se of moscow), slovak (jj, town of cadca, using old czech tesla tooling) - all had very rough starts making tubes for the high audio market and all have had various waves of quality challenges.... those of us who have been tube users over the decades have bad memories and scars from ALL of them as they got their respective acts together, many fits and starts affecting different tube types at different models

2 - as time passes these makers have evolved, their processes have improved (for their own good, more than ours, as they can’t make money with poor quality/high reject rates at their plant or from their distribution channels), so quality has been steadily improving - as always, this is a moving target -- now with covid, the supply chain has been interrupted again, so more uncertainty on tube output and quality - still, all these makers take shortcuts in materials used (a critical aspect) and manufacturing steps to save $, the quality mindset is not what it used to be, when tubes were made for critical/military applications

3 - given the above, it is key for us as intensive users to have a steady dialogue with trusted vendors... the few good ones properly test what comes in (they don’t want customer returns either) to see what is what, if the batch is good, if they sound good -- the not so good ones who don’t test themselves at least see what comes back when they ship product to customers - they will tell us what is good, what is iffy...

4 - all three makers are utterly savvy capitalists, so they rebrand (some bulk distributors rebrand too... mesa, groove tubes), make ’premium’ tubes, using premium or old lovely brand names they bought rights to (tungsol, genelex...)... some of these are worth trying as these represent the best of what these makers can do -- more qc/screening etc etc... so if the prices are within reach for us, it is a win win - they sell their best stuff for more, make more $, we get their best stuff even if pay through the nose for it

5 - the notion of the best tube is a non starter - it is personal, situation specific and gear/system specific - what is the best wine? best steak? best car? --- in general i would say chinese tubes seem to play a little brighter/thinner, russian tubes have a fuller more solid sound, but maybe less ’air’... jj/slovaks are closer to russian tubes, but to be honest it has been a few years since i tried new ones, as they burned me quality wise most recently -- there are always exceptions and ymmv, as always