Devy has been all over the place musically, so I'm not sure anyone can give you a single "go-to" album.
Ghost and Ki are the new-age, mellow Devy.
Addicted! and Epicloud are the poppy, upbeat Devy.
Deconstructed and Physicist are the brutally crushing Devy.
Ziltoid and Ziltoid 2 are the good-ball cheesy Devy.
Terria, Synchestra, and Accelerated Evolution are the most "contained" Devy, with a more focused, serious attention to the music.
Seriously, Devin has been so all over the place it's hard to say WHAT to check out. Best bet might just be the recent live album (Retinal Circus) as it touches a bit on everything.
Devin is one of the most genuine, energetic, honest musicians out there, and will be one HELL of a show. The man is an absolute natural showman, and brings it live like no one else.