I thought about this for too long and came up with this list. What I found is that there are "big" cool books that have high dollar value and "little" cool books that have low dollar value, but equally high "want" value. In that scenario, the low dollar stuff tends to win out because it's very unlikely that anyone would be willing to make a cash offer strong enough for me to part with the book. I need to come up with some fancy term for the "dollar-to-coolness ratio".
Battle Front 23 -- River City copy. Great example of the era. I struggle with a number of killer Atlas war books, almost all with Heath covers. I settled on this one over a few others (e.g. War 11, 23, Battle Front 15, Men's Advs 20, etc.) due to the fact that I've seen or know of a few really nice copies of the others and I've never seen one to compare with this particular book. None of mine are going anywhere, but if you were ripping them out of my hands I might hold this one the hardest.
Bill Battle 3 -- the epitome of anti-communist absurdity. Lurked for this copy for years going back to when Mick showed me a copy back in '96 (oh, my arthritis!)
Journey into Unknown Worlds 49 -- Heath, Robots, and alien invasion... what's not to love?
United States Marines 8 -- about my favorite 50s Korean war cover. So nonchalantly gruesome.
Green Lama 2 -- Certainly one of Raboy's best, if not the best. Incomparable Church copy.