Long time Daddario user here.
My general observations over the years:
Ernie Balls - Break frequently, there's a reason these are always the strings you get with magazine subscriptions, cheap, cheap, cheap.
GHS Boomers - Used these a couple of times, tough as hell never seemed to break. Can't remember how they sounded though.
Rotosound - Sounded a bit too "warm/dull" to me, this could be marketing/brand perception playing tricks on me though.
Dean Markley - Really nice, seemed very bright and high output. Really fancy trying these again to be honest.
Daddario - Sound good, durable, not had a complaint about the and I've been using them for nearly 10 years.
Dunlop - Tried them once, seemed about the same as Daddario to me.
Has anyone ever tried stainless steel strings for electric guitar btw? I've bought a set to give a go so might do a comparison when I get the chance.