Killa Tay is my favorite rapper, by far.
It really depends on what kinda Killa Tay you're looking for, cuz he's almost been like two diff. rappers in his career.
Mr. Mafioso and Snake Eyes are my two personal favorites, mainly b/c I'm a bigger fan of the super-hardcore gangsta rap. Mr. Mafioso is just a banger all the way thru.
His other albums Thug Religion and Flood The Market are definitely worth picking up though. I feel like you can't go wrong with a Tay album.
You should also look for Bully's Wit Fully's 1, 2, and 2.5
Dosia- Waiting To Inhale
Killa Tay Presents: Thug Thisle
and there's more I could go thru, but a nigga's mind is a little slow right now.