The two ZZ Top albums are very different, Eliminator has a very 80's sound but damn those tunes are seared into my mind now. Tres Hombres is dirty old school ZZ Top. Grab Deguello while you're at it. Even better and it just rips on vinyl.
Both CSN(Y) albums are worthy, Deja Vu is essential. The way those voices play off each together and come together is amazing. Some great guitar licks on this too from Stills.
Fisherman's Blues is a masterpiece imo but I can see why some people wouldn't get it. Ever. It needs to be listened to in whole. Lots of introspection on that album.