I use d'addario strings and have done for 10 years now. I see no need to ever change as they've always been very good and reliable. I bought 10 of these spares just incase I break a string on stage and need a quick change without opening a whole new pack although I'm glad to report I haven't used a single one so far!
i started to use Daddario strings 10 years ago and i still do. I always have 3-4 009 strings in case mine would break but actually it is not so easy. Usually i change the whole set (because the strings get old) and the 009 is still there.