Also D'Addario all the way. I find they're consistently good and relatively inexpensive. I buy them by the furlong from Elderly Instruments. Much less expensive than buying them locally.

EJ45 (normal tension) or EJ46 (hard tension) for my Oribé concert classic. Either sound good, but I think the EJ46 have a little more carrying power and sustain.

EJ44 (extra hard tension) for both my Arcangel Fernandez flamenco and my GO-GW nylon-string travel guitar. The Arcangel has a very low action like a good flamenco guitar should (butter-soft), but with anything less than EJ44s, I get a bit of buzz. The buzz is okay if I'm only going to be playing flamenco (part of the characteristic flamenco sound), but since I like to use it for song accompaniment as well, I use the higher tension strings to mitigate the buzz. The GO-GW travel guitar is short-scale (23 ½"), so it needs the higher tension strings.

EJ16 (light tension) on my steel string GO-GW travel guitar. Also short scale, but lightly built, so even though it's small, it sounds like a real guitar instead of a dulcimer.

Probably not much help to people who play D models. . . .

Don Firth