300B or EL34 is a better well rounded amplifier

That all depends on your system and your tastes...and the individual amp. The only comment I am sure on is that most EL34 amps have more power than most 300B amps.

It really depends on what SET amp and speaker combination you put together. With the right 300B amp, and high sensitivity speakers, the 300B can play most genre's of music very well, much depends on the amps power supplies.

A good SET 300B will deliver a high quality of music not made with EL 34 amps. The EL 34 can make very good sounding music, but I believe the best of them still fall short of what a good 300B can do.

I was switching back and forth between an SET 300B, and a VAC PA 35.35, that was factory-upgraded, and had all NOS tubes (Telefunken small tubes and Mullard ouput tubes).

I got a great deal more enjoyment from the SET 300B, so I just sold the VAC.

This has been my experience, for what it's worth.

Regards,
Dan

Well there is no correct answer to a question like this, just too many variables in play. I would prefer an excellently implemented el34 amp over a run of the mill built 300b. All I can offer is this, if both are designed and executed to a high level I`d choose the 300b SET without hesitation.Of all the different topologies I`ve heard over the years, OTL,SET,PP tube,solid state, class D etc. IMO the SET has provided the most nuanced, musical honesty,realism, true to life emotional experience and presence of them all.The SET was noticeably the least mechanical and electronic sounding{next best in this regard was an OTL] That`s simply my point of view based on actual listening. You and others could certainly reach other conclusions of course.The SET amplifier must have good quality power supply and output transformers and matched with a suitable speaker to appreciate its full potential[generally true for any amplifier].Good luck to you and just trust your own ears, that`s what I did.
Charles,