What's the best smoke you've had that is no longer available? Doesn't matter why; victim of the "boom", single year vintage, whatever.
Far ahead of the pack (for me) is the Napa Reserves gifted to my by Slim some time back. Best cigar(s) I've ever tasted. Period.
A distant second is the original Aristoff series. Charlie turned me on to them and I emptied the last shop that sold them. Haven't been able to bring myself to try the new version.

La Escepcion Series II

This ones easy for me the XXO Mini Beli's by Tony B. at clearence prices,first a 5 pack then two boxes and GONE!

I smoked through the first box in less than a month,was going to order two more.GONE!!

I still have 15 or so left,might have to dig deep in the cooler and smoke another one,about two years old now.Seriously I'd rather smoke one of my PAN's or a cuban or Opus,then smoke another XXO.Man they are GONE!!!

Agreeing with JJ - those XXO's were excellent (the discontinued T.B. ones; not the new ones). Also, I'd have to say the Flor de Florez Cabinet Selection - these are still on close-out, and great as a cheap cigar, but not the premiums they once were during the boom. My #1 answer to this question? The Tamborils (naturals - white band)! During the boom these were great mild cigars; now as close-outs, you know the story.
Let's see, I'm coming up with more.... Did any of you smoke Indian Tabacs before the Habana 2000 wrapper? Those oldies were great! And... do any of you see Petersons any more? I liked those way back when.

Victory Spirit 1996 Vintage

The new Aristoffs are quite good, especially the Aristoff Black, which i find superior in every way to the original.

Ditto on the XXOs. The original Don Linos long ago were mighty good, the newer originals don't seem the same. Also I thought the old Sinatra's(light wrapper) were a decent cigar, the new ones taste like a different cigar.

Charlie....step away from the Tamborils! from any time, lol!