300B or EL34 is a better well rounded amplifier

Which one can play all music genre better?
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.

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.
If you have a lot of money the 300b without a doubt.
If you don't ,stay away or you will soon have no money and a divorce.

No witticism intended.
Jeez, this thread makes me wish I didn't just buy a VAC PA 35/35 EL34 tube amp. ;^)

Maybe one day a 300B SET amp will be in my room, but I'm probably going to need the prices to come down on them and/or maybe some different speakers too......we'll see.

Not to worry JMC, a EL-34 makes everything sound better.
A VW Pasatt might not be a Benz E-350 but you still can ride from Chicago to LA in one with style and comfort.
good point, I still have an el34 PP amp and It does sound good. It`s just with direct comparison that the differences become apparent in favor of the 300b SET. I can still enjoy music with the eL34 amplifier.
A VW Passat to a Benz E-350?? C'mon, really??? Not even like comparing a Beemer to a Benz? That's even more disappointing..... :(

I might as well just get an Onkyo receiver, see to me, that would be like comparing a Passat to an E-Class Benz.
Could say Audi A-4 , just a Passat in drag.
Drive a Passat TDI Diesel some time, one sweet car !
BMW = Big Money Wasted
I concur with your observation about the BMW, though my VW experiences have not been good either. Hence my response about comparing a VW to a Benz. Though to be fair, I have not driven a TDI Diesel.
All German cars are over-engineered, when they get things right they get them really right, when they get them wrong, well...., just get a Honda if reliabilty is your goal.

Few years ago I rented a E-class Benz at Frankfurt airport at
Christmas time with 16 kilometers on it. Off-gassing from the seats was bad, rolled both back windows down, they stayed that way for two weeks driving around Germany in winter as neither were on their tracks.
This is the most entertaining and hilarious thread I started. I haven't had the chance to audition the 300B. Now I am very curious. Wish I can compare them side by side. Thanks for all your awesome responses.