What's The Keeper In Your Collection?

I mentioned yesterday I'd been reading some Australia-era X-Men comics. I was doing that because it was time for another periodic culling of the collection. Going through trying to find comics I don't really like any more, or that were a disappointment.

What happens a lot is I get a complete run of something, then reading through it all reveals certain weak points. Particular threats or plots I wasn't interested in. Issues by fill-in writers that are just marking time until the regular writer gets back, fill-in artists doing piss poor work. With newer comics, it's more the story is stretched over so many issues that there are some comics that are superfluous. Not enough happens to make it worthwhile. That's how my Ultimate Spider-Man collection is a third of its former size.

Here's my question to you: Are there any series you own, or specific stretches on a title, where you wouldn't consider getting rid of any of it? Like you might, either for monetary reasons or space concerns, get rid of every other comic, but you ain't touching that set?

For me it's GrimJack. I still haven't sat down and read it the whole way through since I finished collecting it, though it's on the to-do list. But the slow-building of the world, of Gaunt's character, the way every issue has something happening. Even the issues that seem like standalones, or rather inconsequential, can end up being important in some way. Gaunt himself hits me in a particular spot, his doubts and fears, his attitude all mirror questions I have, or illustrate dangers in some of the ways I've thought in the past.

What about you?