Depends what part of AFI you want them to sound like, and what phase of AFI you liked.
If you like old AFI, you might want to check out Cold War, Ed Gein, From Autumn to Ashes or Poison the Well.
If you like new AFI, you should probably check out A Static Lullaby, Atreyu or Scars of Tomorrow, but don't blame me if you get really tired of them very quickly.
If you just like Davey Havok's voice, check out Son of Sam. It was a single release side project he did with members of the Misfits.