These are a few of my favorite strings

For years I played Martin Marquis 80/20s, although I'm not against trying different strings (see here for my thoughts on Martin Monels; a.k.a. Retros) and have been playing D'Addario EJ12s recently.

A few months ago picked up a few sets of strings made by the Guadalupe Custom Strings (update 8/13/18: now The Gabriel Tenorio String Company); these are handmade strings, wound on a round core rather than hex-core, and at $18 a set they weren't cheap. GCS makes all sorts of cool strings for various instruments, and I liked their guitar strings a lot. And I like supporting artisans who produce unique products. But last I checked they were up to $25 a set in the gauge(s) I prefer, which is more than I want to spend. So I just picked up a stack of DR Sunbeams, which are also round core strings available at about $7 a set. We'll see if these stick for a while.