I think I've deleted Twitter (entire account, not just the app) three times. I technically have an account now, but I only use it to ask questions of businesses. It's been over a year since I wiped my last real account, and I'm never going back. Facebook was purged once, and I never went back.
The only one I still use is Instagram. I have one friend who posts text statuses, just screen shots of Facebook, but otherwise the limitation of needing a picture makes it so much more tolerable.