300B SET or EL34 SET

IME, a true triode tube like the 300B will sound better that an EL34 tube  "wired" in triode.  Low level listening ability is more to do with proper speaker matching than tube type.

But if we just look at the characteristics of the tube itself; which tube has most punch in the bass, or best bass?
What I understand from your answers the hights also goes to 300B.

The EL34 will produce more power which could translate into more bass when driving a less efficient speaker.  A 300B amplifier takes more care in matching with the appropriate speaker. 

@glennewdick  The 300B tube was designed for extremely low maintenance and a very long life.  As an example, WE300B are spec'd for 35-40K hours, therefore, making their cost of ownership quite inexpensive when you amortize the initial cost over its expected lifespan.  I know many individuals who have ran the same 300B for years, and the tubes still sound and test like new. 

The Chinese looked at what westerners were willing to pay for vacuum tubes, therefore, they put lipstick on a pig, used names of historic brands like Western Electric and call them replicas, put them in fancy presentation boxes and coated the internal and change the shape of the glass....and charged a premium price. Clearing targeting the North American market.  The tubes sound okay for new production, but can be bettered in most cases by NOS / OS tubes.