For my money the panasonic TX range was generally probably the best consumer level. I'm pretty sure they all had sub 30ms input lag. Some sub 20. You'd have to check per model for exact detail and features though. I'd presume if you're picking one up 2nd hand you'll be looking to find one of these... no such thing as viewing angle problems, good colour, decent general picture, real good fps conversion for film if that's a thing for you...
Two words of caution if you're not familiar with plasma in general - i) Use in darkened environment. ii) I must note I seem to be one of the few people that (at least on bright/high contrast image changes) that see the screen flicker/flash due to how a plasma posts it's image (nothing to do/fixible with hz refreash rate unfortunately - extremely fast/subtle sensitivity, probably in excess of 144hz) ... Most people don't seem to be effected by this at all, and I find it's often of minimal consequence even for people like me in your typical living room usage, but for some people it can be very bad.
And then there's the pioneer 4:3 plasma that appears in said ode thread: http://shmups.system11.org/viewtopic.php?f=6&t=43256
Pretty rare... though there have been a couple changing hands regularly around the arcade/shmup forums
OLED degredation/decay has put me off anything other than LCD recently... but if you get 5+ years warranty I guess you can't go too badly wrong up to the kind of prices you see now... and I would love a reasonable OLED 4k desktop... aforementioned input lag seems to all be 40ms and up though...