EL 34

As noted, If you have not tried them already, listen to the new production Genelex Gold Lyon KT77s.  Some of the vintage EL34s are getting to be long in the tooth or end up saving them away anyhow.  

The former EL34-BSTR made by Shuguang for the Ruby brand was actually a very nice valve in my former Cary amps.  Would still recommend either of these when mothballing the vintage supply.  

Just heard a well burned in quad of PSVANE KT88s on my buddies upgraded integrated amp, paired with good small signal vintage tubes, sounded really nice.  Quite surprising actually, as good as any EL34 I had heard to date new or vintage.  .      

I have a set of the Genelex gold lion kt77's I've tried them in two amps, both push pull, and find they are inferior to the similar gold lion 300b by a significant factor. 

I find the top end to be rather harsh and not very extended. I'm using a three way horn system so its rather reveling in the top end. The basic Messa branded el34 is better in many ways, IMO, not perfect but for cheep tubes they work rather good over all. 

Now maybe the kt77 are not broken in but I don't think they take that long and I've tried them in two amps now with the same result. I really wished they were better as I have a set of the Gold Lion 300b variants and they are stellar. 

I'm now on the fence if I try the Gold Lion 2A3's in my new amps.

I have a Leben CS600.
I believe the KT 77s would be an option.
I would favor a smooth top end

@mpomerantz a jeffsplace review replacing the stock electro harmonix EL34s with Sophia Electric EL34 and KT88s, on the Leben 600X. Gives an idea of what room for improvement might exist over the stock EH for your type amp.  Other member feedback comments below the article too, fwiw. https://jeffsplace.positive-feedback.com/leben-cs600-cs600x-tube-rolling-with-sophia-electric-vs-ele...

RAM tubes :-) Roger Modjeski but still going strong w super matching and testing, $45 gets you a killer valve