I've discovered that the Dual E280F in the Quintessence produces the most balanced sound in terms of dynamics, transparency, and tonal density. It conveys the music with a deep emotional resonance and avoids sounding thin. The details are present without feeling forced or overly pronounced.
When using the Dual 280F, it's generally best to mix tube manufacturers, as using the same manufacturer as Dual sometimes works and sometimes doesn't. It's a trial-and-error process at this point and not very predictable.
As for the 6J11P, they are cost-effective and offer excellent sound quality. They produce a more linear sound, clean bass, and a slightly less thick tonality in the midrange. I personally love this pairing and often rotate between them.
Regarding the E282F, I've found that using a single tube in each amplifier works best for me; duals don't seem to work as effectively. It takes some time to bias this tube to find its sweet spot, but the effort is definitely worthwhile.
I haven't tried the E180F or the E810F yet (I plan to do so later). For now, I've found my sweet spot that works best for my ears and don't feel the need to experiment further at the moment.