Whoa! The first 2 albums that Collins took over ('76-'77) vocals-Trick of the Tail, and Wind and Wuthering, (my favorite) were great albums, with no pop songs. I've stated a few times the last year about the '81 album Abacab, being the last album by Genesis that was worth having. It's a decent album. But the album before- Duke, is when Phil started writing some lyrics. They were ok songs, but the writing was on the wall, that's for sure. Any Genesis from '70 to '77 is where you will be satisfied.
To me:
Best Gabriel era album-Selling England By the Pound, and Nursery Cryme
Best Collins era albums-Wind and Wuthering, Trick of the Tail
And if you decide to get a Genesis album, get the remasters with the DVD. The Gabriel era are not out yet.( and I'm really chomping at the bit waiting for those albums!) The extra disc has the album remixed in 5.1, and archival footage, videos, band member documentary/interviews, talking about the album. The Duke, and Trick of the Tail discs have live concerts on them. The 'And Then There Were Three' disc has an interesting '78 Tour Documentary on it, that is at least an hour long.
Genesis truly were an amazing band from '69 to '81. The 80's is when their shows cut almost every pre '78 material out of there setlist, except for 2 or 3 songs at most. Once Phil's first solo album did well, his head got so fucking big, and the rest of the band let him pretty much take over, and turn them into, to me, just another Phil Collins solo group.
As for Yes, (I'm probably the biggest Yes fan on the forum here) they are almost in the same boat, as for changing in the 80's. But, the 3 albums Drama, ('80-The only one without Jon Anderson on vocals) 90125, and Big Generator ('83 and '87) were stellar albums! Trevor Rabin took over guitar on 90125, and provided a hard rock, with a little mainsteam (a few songs were on the pop side) sound to the band. Their 70's peak prog moments were '71 to 77'.
My 2 favorite Yes albums are '73 Tales From Topographic Oceans-a dark, cosmic, atmospheric, mystical album with four 20 minute songs, that are really one 80 minute song in 4 parts. And '87 Big Generator- Trevor Rabin's second with the band, and he created a balance musically with this one, by bringing in more of the 70's melody, but also keeping it rhythmically heavy.
I would start with the '72 albums Fragile, and Close to the Edge albums. Critics and many fans cite these as the best Yes albums. Though not My favorite Yes albums, both are masterpieces. They did have a few strong albums in the late 90's with the classic 70's lineup, The Ladder, and Keys to Ascension I and II.