He should continue his streak of undefeated fighters (Wach, Pianeta, Povetkin), so I say Pulev, Jennings, Fury, Helenius/Boytsov, and Wilder.
Honestly someone like Fury, Wilder or even Helenius, just someone big he can't impose his weight upon and clinch 24/7. You know exactly what would happen if he fought someone like Pulev or Chisora, he'd just hug them into submission.