I think they're still available as of now, yeah? When I go to the website, I can add one to my cart. So over four hours. Demand is finally being met. That's great!
I wouldn't say that. I like the Archetype Valve Boost more than most Broughton Audio offerings: Dystopia, Sunder Fuzz, Maestro, Azure Drive, Fliptop, Rumblefish, Scorpion, Terraformer, etc. But, in my thinking anyway, such a comparison is kind of silly because the AVB is a boost and the FFXL is a utility pedal and the Sunray is a tube overdrive. They do different things and, when used properly, they each succeed in their own way. That said, when I approached the AVB as a boost I did not love it as much as I wanted to because it's not gritty enough to be a true dirty boost and it's too colored to be a transparent clean boost; but when I approached it as an end-of-signal tube tone sweetener I really loved it so that's what I now use it as. I also really like how it stacks with the Valve Champ. Those two work especially well together: the AVB tightens up the Valve Champ while the Valve Champ adds some more low-end weight to the AVB.
I don't believe there are enough items to rank as you ask (and such a ranking would only reflect my musical ecosystem and my ears anyway). Besides the Super Stack, is there another Broughton Audio tube boost? The Transboost, Solarian, Fliptop Boost, Studio Boost Mini, Amplitude, and SVBoost aren't tube boosts and the Sunray, Quicksilver, Valve Champ, Archetype Valve Preamp pedal, EDTI pedal, and ATD 12AX7 have tubes but aren't boosts. I haven't played a Super Stack, but my understanding is it aims for a Fender EQ and the Archetype Valve Boost aims for Broughton Archetype EQ profile. They're just different *shrug* "Better" is up to the user's musical use case.