D'Addario XL(10-46) on my electrics
Martin, I have 2 Martin guitars right now with coated strings, but I most go with D'Addario They are either Phosphorus Bronze or 80/20. 12 to 53. Nothing super heavy on the bottom ends. Their coated string are pretty good too, but will cost ya.
Ernie Ball Slinkys, I have used, but I normal go with the D'Addarios these days
I also like the Chromes on a couple of Jazz boxes I have. I believe the are 13's.
Mandolins I also use D'Addarios.
Electrics and acoustic I just by the Pro Packs or what ever they call the 10 sets now. You save a bit of money, buying in bulk. They also have a 25 set shop bulk pack but they are not vacuumed sealed.
I once kept a set of Elxirs on a bar gig acoustic on for a year. It became a challenge to see how long they would go before the became total crap and frayed.
I do think I broke a few along the way and some one string frayed so badly it needed to be changed. Talk about being cheap. Hell, 6 bucks is 6 bucks.