Having spent a decent amount of time either living or working in all of those regions, definitely Guilford and Madison. They're the least crowded-feeling of any of the towns you listed. Madison has one of the nicest town beaches in the state (Surf Club), and Guilford has one of the nicest town greens along with town beaches on both LI sound and a beautiful lake. They also have the easiest access to New Haven, including a rail line. New Haven is a better city than Hartford in nearly every way.

If those towns are a bit too sleepy, my next pick would be Glastonbury. It's nice and has a more built-up downtown area, and it's close to Hartford.

Personally though I can't stand the Farmington valley area. The main roadways there were never designed for the amount of people that actually live there. It feels congested but in the woods, imo it's kinda the worst of both worlds. Anything on route 4 anywhere around commuting hours kinda highlights my point. Taking 84 into Hartford also sucks in general through that area. The canal trail is nice, though, so it has that going for it.