Given that there's a smaller sample group on annihilus than on bnet, I'd argue that BiS items are widely unknown for most slots on most builds. Also, the BiS items are going to vary by whatever may be the specific smiter's gimmick. For example, husk/bramble and a plaguebringer would be best for a poison smiter, while tyraels or sanctuary balance may be BiS for a thunderfury/frostmourne wielding smiter. I haven't bothered trying to build on a physical smiter since I mainly farm dreamlands and mappo is a bitch.

I've had tons of success with a poison smiter, which that build was highly flushed out here. I subbed dragonscale with e exile and my survivability got a bit better.