You have several decent choices as your commander, but I feel the recently printed Astor, Bearer of Blades is the best of the bunch
It's so popular because it only costs 3 ink to play, and its two abilities allow you to both gain lore and draw cards, two things that help you win the game
A single Thopter token won't get you too far, but multiple Thopters over the course of a game add up
Gix Tempo Gix, Yawgmoth Praetor is essentially Mono Black Edric, Spymaster of Trest that has a slightly weaker card draw engine (you have to pay life) and weaker colors but instead comes with a built-in finisher, trading your individually weaker cards of 1/1 evasive creatures for actual haymakers and win conditions of your opponents' libraries
You can also include Rhystic Study in that list too
In this game, challenging is the control strategy, while questing is the aggro strategy