The most impactful that Id personally pick would be: Deflecting Swat, which is always good when you need to protect a Commander that attacks for value and damage
That's 16 more than Toph, Hardheaded TeacherToph, Hardheaded Teacher or the more mundane Uncle IrohUncle Iroh has in Gruul, 15 more than Sokka, Bold BoomerangerSokka, Bold Boomeranger in Izzet, and 13 more than Guru PathikGuru Pathik and The Lion-TurtleThe Lion-Turtle have in Simic, to say nothing of the multiple single-color Lesson commanders that have access to a fraction of that (return readers will note that I didn't even mention Lessons when I wrote about Gran-GranGran-Gran last week)
Plus, Jeskai artifacts are always fun
His first ability has serious political implications in a game, encouraging your opponents to attack each other instead of you for the card advantage Gix provides
Teferi's Protection | Illustration by Chase Stone With the introduction of foil cards in Magic and other trading card games have come a horrible problem, and thats card curling