I'm sure a thread like this has been done before. The days of 12" LPs were the best times for recordings. The cover art was large and often quite beautiful. CDs can't compare. Some people today, all they want are the mp3s and screw everything else. Can't blame them, I guess, since the CD covers are too small to see and the lyrics and other print is too small to read. Here's a very small sampling of the the vinyl I've owned over the years whose artwork really stood out for me. Feel free to post yours.
Anthony Phillips - The Geese & the Ghost
Gentle Giant - The Power and the Glory
Renaissance - Turn of the Cards
King Crimson - Lizard
Tom Waits - Small Change
Eddie Cochran anthology
Tar Babies - Respect Your Nightmares
Fripp & Eno - Evening Star