(11/17/2017) If each player controls a Consecrated Sphinx, their abilities will cause each other to trigger until one player chooses not to draw cards.
Reckless Stormseeker, the new Werewolf from Midnight Hunt , is also a great option, and one thats tutor-able with Imperial Recruiter
This is mostly due to Torture Pit, which is a kind of effect you see a lot in Commander these days
This flexibility is what makes it the number one choice here, though Tyvars Stand is a close second, and might be more relevant to you if youre predominantly running creatures or a deck focused on Commander Damage or Infect
That is a lot of Teferi
It benefits from costing less than Sigiled Starfish, allowing you to block small aggressive creatures earlier, but is it worth it