X-Men is something I wish I had more of but the issues I want are expensive. X-Men are great, but they don't pull me in like other series and titles. I only have 15 issues from the initial series, #57 being the coolest one.

I have maybe a dozen other X-related books, some X-Factor and a couple X-Force. I also have Morrison's run, which I have yet to finish. Oh and the graphic novel God Loves, Man Kills. I really enjoyed that one.

Issues of Uncanny X-Men - #130-137, 150, 165-167, 173-334

After quite a long break from the merry mutants, I picked X-Men back up during the Messiah Complex event and have pretty much followed them ever since through the resulting volumes.

As for X-Factor and New Mutants, I have the first ten issues or so of each series, then a scattering of issues from later runs, mainly the issues that were part of the wide X-line crossover events of the time. I still have New Mutants #98-100 so I remember Deadpool when he was a mere pup.

X-Force #1-20

Cable #1-20

X-Men 2099 #1-10

Generation X #1-15

X-Men #1-41

Exiles #1-27


As for trades:

Essential X-Men #1
Essential Uncanny X-Men #1-6
Essential X-Factor #1
Age of Apocalypse #1-5
Cyclops Retribution
Days of Future Past
All-New X-Men (vol 2) #1-3
Avengers vs X-Men
Wolverine mini
Messiah Complex
From the Ashes
Dark Phoenix Saga
Asgardian Wars
Epic Collection - Second Genesis
Epic Collection - Fall of Mutants Vol. 1

Novels:

X-Men Chaos Engine Trilogy by Stephen Roman
Mutant Empire Trilogy by Christopher Golden
Codename Wolverine by Christopher Golden
Avengers & X-Men: The Gamma Sentinels Trilogy by Greg Cox

 

I'm way behind when it comes to Marvel's mutants, but I have a few keys worth mentioning.

Tales of Suspense 49 (first x-over, same date as X-Men 3)
Fantastic Four 28

Giant-Size X-Men 1
Amazing Adventures (1979) 1-10
Uncanny 147-148
God Loves, Man Kills
X-Men 1

I never was either as you can see from the disparity in sequecial issues on my list. The best and favorite thing of the X-Men is the Brood and Age of Apocalypse. Love the Brood. They're like the Alien of Marvel.

I think this list is incomplete but here's what my records show. This is the original 1963 series:

4, 12-15, 17-18, 21, 23, 26, 28-31, 33-36, 38-61, 64, 67, 69, 71, 73, 79-91, 99-106, 110-112, Special 1-2, Giant-Size 1.
(extra copies of 54, 69, 71)

Pretty sure I picked up Giant-Size #2 at some point.

For Uncanny, which I am assuming is what you are referencing, I have the first two Omnibus editions, collecting all of the original series of stories, and floppies of #10, 13, 51, and all issues from #94 through the end of the original series.

As for the other titles, I have complete runs of X-Men/New X-Men/X-Men Legacy, X-Factor, Excalibur, and New Mutants, plus the first 40 issues of Astonishing X-Men.

Pretty much just the earlier years of the Claremont era, from around #95 up to around #150. I'm missing a few issues of it, though - some of the the first few Cockrums, most importantly. I've recently started thinking about continuing on a little farther, too, since almost every X-Men reader here says the series was still pretty good past the point where I stopped back in the day. I'll probably try at least up to the end of the second Cockrum run. After that, I'm not too sure about the artwork, even if I end up still interested in the stories and characters. But eventually, if I see them cheap, I'll get a couple of the Paul Smith issues to see how I like them .

I'd also like to get some of the old, pre-Claremont X-Men, mainly the ones I remember reading as a kid - the Stranger story, the Ka-Zar, the Juggernaut, ... I think those were the three big ones I recall. I didn't read as much X-Men as I did some of the other Marvel series. Also the Steranko issues, and maybe the Neal Adams, both for the artwork. They tend to be expensive, though.