If you don't have any problem with horror check out Corpse Party. Saya's Song is pretty damn sweet but it's not ported to the PC, it's my favorite visual novel. Oh, it's a horror-loli game however. I really liked A Drug That Makes You Dream and I've almost 100% Katawa Shoujo and it's so far pretty good. Both are non-loli.
I'm kinda newbie with visual novels so I'd recommend asking for recommendations here or just browsing here.