Used to use Dean Markely Blue Steels... and switched to D'Addarios of various gauges in the early 90s. I have never, not once, broken a string with the D'Addarios. I've used them ever since.
I've tried Ernie Ball, GHS, off brand and other strings. There are some great ones out there, but the D'Addarios last a long time, sound great, and don't break.
Unless quality goes downhill, I'll be using these from now on. Currently using the .009-.042 set. Used to use .010s on all my guitars, but got tired of putting in the extra fight for what was just a little more fullness in tone. Who knows, if I can find them, I may even try a set of .008s.
Guitars:
Fender 2006 MIM Fender Stratocaster HSS in 3TS
Ibanez RG 570 with a bridge Invader
ESP M II Deluxe with a Tune-o-Matic bridge
Eleanor, the magical, mystical Road Worn wonder Tele
Blackstar HT Club 40