I noticed an article on www.ultimateclassicrock.com which was a list of what they consider to be Rock's Most Criminally Underrated Albums:

http://ultimateclassicrock.com/underrated-albums/

There is no mention of the Eagles here but I thought this might prove quite an interesting topic for discussion.

The list is not exhaustive and contains the following albums:
The Who Sell Out - The Who (1967)
Vincebus Eruptum - Blue Cheer (196
Presence - Led Zeppelin (1976)
Waiting For Columbus - Little Feat (197
Tusk - Fleetwood Mac (1979)
Done With Mirrors - Aerosmith (1985)
Yeah! - Def Leppard (2006)

I only own 2 of these 7 albums - Presence and Tusk - and I personally disagree with the inclusion of Tusk. I have mentioned my feelings about this album before and while I do like a lot of the songs on the album (I love Sara, Think About Me, I Know I'm Not Wrong and the title track, for instance) I would rather that Lindsey had left his more experimental works to his solo career - they just aren't band recordings - but I also feel that most of Christine McVie's songs were weak and weren't as memorable or melodic as her tunes from the previous two albums. In fairness Stevie does more than her bit for the album with 4 great songs out of 5 (Angel is good but lacks something). I certainly cannot agree that is best digested as a 75-minute album as side three has three consecutive songs which I would skip - in my view That's Enough For Me is a pure throwaway, Brown Eyes goes nowhere and Never Make Me Cry is so dull that I actually sometimes think it's called You Never Cry Like A Lover or Don't Cry No Tears (I never get the titles of those two songs mixed up though. Can't think why!). In the past I have made a single album playlist for the album which I find much better.

I agree more with the inclusion of Presence, as Achilles' Last Stand is terrific by the standards of any Zeppelin album while I also think For Your Life, Nobody's Fault But Mine and Tea For One are strong while Royal Orleans is also quite good and quite amusing. However, I also think Led Zeppelin III and Houses of the Holy are somewhat underrated apart from one or two iconic songs, and these albums are better than Presence.

A couple of non-Eagles albums I would suggest:
Communique by Dire Straits (1979) - this to me is perhaps the most criminally underrated rock album. Often (wrongly) written off as boring, it contains three of my absolute favourite DS songs, these being Once Upon A Time In The West, Where Do You Think You're Going? and Single Handed Sailor, which is in my personal top 5-6, and several other strong songs such as Lady Writer and Portobello Belle. Mark Knopfler's guitar has a great warm tone throughout and the lyrics are up to the usual standard.

Atom Heart Mother by Pink Floyd (1970) - Musically very satisfying for the most part and not as impenetrable as is generally suggested. The side-long title suite is the only song that I would say is difficult to get into, with the shorter songs all being relatively accessible. The title track isn't perfect but the best sections such as David Gilmour's bluesy solo midway through are very, very good indeed, while the three shorter songs - If, Summer '68 and Fat Old Sun - are all strong, as is the IMO unfairly maligned Alan's Psychedelic Breakfast, a song that is far more musical than its title suggests.