What about the option, only storing the good ones. I'm not going to waste TB of bad anime. So, only the good ones for me. However I still watch rarely anime, as I read or have rode the manga already before the anime comes out. And I rarely watch an anime were I've read the manga about.
For scanlation I do the same thing however their are way more good manga's than their are anime.
Also with this I also store the stuff as back-up for the official copies I have.

As deadphoenix says, I think there's a huge gap between storing "everything" and "only a few". Went with everything, because I keep 90% of the stuff I download. Though that may be because I'm picky with what I download in the first place.

I'll be the third in a row to comment that there is a lot between "everything" and "only a few".

I archive everything (that isn't crap or mediocre, anyway) ...but only as far as I have harddisk space.
Thus I don't archive that much, at the moment.
*needs new harddrive*
...and I restrict my deletions, for space, to stuff that is easy to re-acquire. (and that I won't want to re-watch real soon)

With manga I archive a lot more, as it takes up a lot less space. I generally don't need to delete anything.
Some series are a bit messy to determine which chapters to get from which group, so I haven't bothered to archive them yet (and just read them from online reading sites), and some are a bit tricky to find a place to download from (or only release via IRC, which... fuck that! Why anyone does that...), but other than that, I pretty much always archive.

I don't even watch anime. But if I were to watch it, I definitely wouldn't archive them, it takes way too much space..

Used to, not anymore, now I just let them pile up and delete from time to time when I need to.

Since now it is faster to redownload them than try and find the media you've written them to, I only archive very rare hard to get series.

Back in the pre-DSL days i saved my anime/comics/movies and so on to have a library and thus save traffic but now everything thankfully lives online and i do too.

Only a few. I used to watch a lot more anime, and thus had a lot more fansubs archived, including all of the Jump Big 3 and others like KHR. Now I barely watch any anime save for One Piece. I only actively save the episodes for that series. There are a few other series like Code Geass that either have some sentimental value or that I will probably get rid of sometime. Besides that, some short series that I intend to give a try also find their way offline. This reminds me of the anime of Parasite that I was gonna watch ...

Only a few for me. I stream most of the anime I watch (if I remember to watch them. I'm so behind on currently airing anime) but there are some that I do download because I know I'm gonna want to watch them again. I like getting the blu-ray rips when they're released for a few series as well. It's worth it if you enjoyed the series and would happily watch the whole thing all over again.

I'm with the minority in this poll. I download every episode (I usually only watch completed anime) and then watch everything (not all in one day. My life doesn't allow me that). I keep everything while I'm still watching it and then delete it after watching the last episode.

Maybe I don't give it the same importance as some people but for me, If I want to watch the show again, I'll just download it again. There's no need for me to be occupying space on my HD...

Half my external hard disk comprises of anime shows and the other half comprises of idol shows. I share those animes with friends plus I feel like its a collection. A really nice collection. The ones I dropped are deleted but the ones I completed stay. Going to go with everything since I am picky when it comes to anime show and only choose to watch what I know I will like.

(But I haven't recently. Ever since I started watching animes online on my tablet, I have become to lazy to open my laptop. )

Used to, deleted all of them. It's just a pain trying to clean out enough space to use daily with all the stuff. Animes got well, pushed down the priority list to keep on hard drive.

watch online. I dont' download anymore

aah I watch and delete mostly because my internet is terrible with streaming. I usually have 8 different animes downloaded at a time so when i finish one, another is set to download overnight haha.