Going back 25-30 years:
These models have a lot of character and a a joy to paint. These sculpts still have the absurd and funny to them, that the models nowadays miss-then it there was a lot of room for fun and laughter, whereas the models nowadays are so grim and serious. Anyway, I still have 10 of these old guys laying around and I will get to them eventually.
from the nineties:
The classic plague marine sculpts from Jes Goodwin. They are good looking, my favorite is the guy with the goggles. I only have these three from that period.
recent models, early 2000's
These are the current line of plague marines. They look gruesome and threatening. Their funny parts have been subdued and there is more gore. Still, great looking models and really fun to paint.
Battle for Macragge Marines turned Chaos
I picked up a cheap set of these recently and converted three to Chaos, to bulk up the ranks. With one Chaos shoulderpad and a rough paintjob, they look the part-i did cut off all the imperial signs. I am working now on converting Spacewolf Terminators into Chaos Terminators.