SET the best?

larry is correct in that output/power tubes critical for SET. The difference between Shuguang Black Treasure and Psvane Acme 300B is like night and day. Shuguang like $250 pair, Psvane $900-$1k pair. The Elrog, WE, Linlai Elite, EML, Takatsuki will all be $1-$1.7K pair.

I'd never purchase budget 845, we're talking 900 volts, some major hurt if these things malfunction.

I have two stereo amps and two pair of speakers. All-tube preamp (Supratek Cortese).

One system is Quad 2805s driven by Quad 909. They have a certain coherence and beauty.

The other system is JBL 4430s driven by humble AES SE-1 300b, with the 12AU7 pre-driver stage modification Dennis Had described in Sound Practices Issue 6. This modification replaces the 6SL7 with the 12 AU7 driving a 6SN7. Given the humble pedigree of the SE-1, this modification is nothing less than Ingenious. Maybe someday I'll hear a higher-pedigree 300b amp. As it is, I love the sound of this thing. Beautiful, coherent sound. The JBLs are 93dB efficient and I listen in the near field, so I'm seldom using a full watt. All kinds of music sound good through my system.

Re-reading what I've written, truth is I don't think I've contributed anything of value to this discussion, other than to say I love the sound of my humble 300b SET amp. And maybe to suggest that you don't have to spend inordinate amounts of money to get a taste of the magic. 

In the mid-late 90’s I had a 2A3 PP amp from Cary audio. It was very SET like in its presentation and would work with not so sensitive speakers. It made several hard core SS folks listen up and take notice.  Too bad the reliability was an issue with these amps, they did sound quite good. I tried bi-amping using the2A3 on top and SS on the bottom..  Never got it sorted out well enough and moved on.. But the 2A3 sound is intoxicating.

Speaking in very broad, generalized, terms, I tend to find pushpull amps to have a "tighter" more punchy sound than SET amps.  But, too much of that quality and the sound seems a bit artificial or "mechanical" and less natural than the more relaxed sound of good SET amps.  For me, for example, KT88 pushpull amps tend to be particularly likely to sound too punchy and mechanical for my taste, but, as with everything in audio, there are always exceptions. 

I like MANY pushpull amps (this would include OTL amps), while I also like SET amps.  It is never as simple as saying one type is better than another.  Right now, I favor my pushpull 349 tube amp over my SET amp (the SET amp costs considerably more), but, in some respects I still do prefer the SET amp--although the bass is less powerful and tight, it sounds more subtly "musical" (the quality of the bass changes with the music and sounds less "same" and "mechanical" as my pushpull 349 amp).  Both sound harmonically saturated, deliver an expansive and immersive soundstage, and sound relaxed and natural while still being very lively sounding; the pushpull 349 just delivers a little bit more of these qualities.  

Speaking in very broad, generalized, terms, I tend to find pushpull amps to have a "tighter" more punchy sound than SET amps.  But, too much of that quality and the sound seems a bit artificial or "mechanical" and less natural than the more relaxed sound of good SET amps.  For me, for example, KT88 pushpull amps tend to be particularly likely to sound too punchy and mechanical for my taste, but, as with everything in audio, there are always exceptions. 

I agree- I tend to see punchy bass as a coloration, since you never seem to run into it in live events. I've played in orchestras, jazz and folk ensembles, rock bands and just not encountered it. I think its the product of an overdamped speaker to a certain degree but I don't think that's all of it.

The distortion signature is what is at play here IMO. Most pentode-based amps employ a bit of feedback, but since they really don't have enough, they have an obvious distortion signature (the amplifier's 'sonic signature'). Some of that includes harmonics of bass fundamental tones, generated by the feedback itself. The ear is interpreting them as 'punchy' (and yes, this happens with many solid state amps too). IMO/IME the way around this is to make sure the amp is as linear as possible, so much so that it will sound reasonably decent with no feedback at all. Only then do you apply the feedback- and then it should be used to control gain more than anything else. With a pentode-based amp I suspect this would mean that the output section is wired Ultra-Linear.

But many pentode output stages really aren't that linear and need the feedback to linearize them. That is a bad move IMO. You can't get rid of all the distortion and if you start with a high distortion amp, the feedback will cause it to have a less musical distortion signature overall when you're done. Amps that have zero feedback have a different distortion signature that tends to favor the lower ordered harmonics which will mask the presence of the higher orders. But if you have no feedback you also have a much more limited range of speakers that are practical with the amp. For more on this see

The Power Paradigm Vs the Voltage Paradigm