I can't say I have a favorite. It's different for acoustic vs electric, and varies from guitar to guitar based on scale length and purpose of the guitar. I don't choose strings for me, I change strings for what I'm doing and adapt my playing to do that. For example, if I'm playing old 60's music, I'll get something pure nickel but slinky. If something jazzy, flatwound nickel heavies. If I'm doing 80's metal, stainless steel boomers. I also change my picks based on the type of music and sometimes even based on the tempo or based on what kind of picking I have to do. For example, if I have to do fast tremolo picking, I'll either use a heavier pick turned to the blunt end, or use a really thin pick, depending on the music. I do that with everything my hands interface with; strings and picks on guitars, likewise I change drum heads and stick weight/length/tips/wood for drumming on different kinds of music.