I havent bought a comic book in almost 15 years, and I dont actually even have many left anymore.
I used to have around 300-400 including Spawn 1-20, most of the first X-Men issues (second series (inc all the holographic character issues,)) The Breaking of Batman, The Death of Superman (inc special editions, comic issues and the full novel) the first few Spiderman issues (the one by Todd McFarlane,) justice league, Team America, a bunch of Punisher, and well, just a shit load of other ones I dont really remember.
I dont know if anyone who is new to comics knows about it, but the Breaking of Batman and the Death of Superman were big deals at the time and IIRC paved the way to a bit of a character revamp for both of them.
For the most part, all the comics I had were released in the late 80s and early 90s. I remember starting to collect them almost as soon as I could read. Eventually I stopped reading them and just collecting them, then eventually stopped all together when I was a teenager.
I had a lot of pretty unique stuff and got a nice chuck of cash when I sold them a bunch of years ago. Sometimes I wish I had saved them but, eh, cant undo it now.
As a general rule of thumb for me back then, it was always DC > Marvel. I wonder what kinda new comics are out these days at times, but I just dont care so much for action like I used to. Would prefer drama/comedy, which is kinda why I dont read those type of comics anymore, but I do read manga.
On a semi-related note, I still have piles of old Calvin and Hobbes, Dilbert and Life is Hell books of comic strips.