Most important criterion: Please no misinformation...
That should automatically rule out Godspeed and DMS (sorry, honestly, but I'm just being frank here). Unfortunately, I think Godspeed is almost a lock. Not hating on either, but it's distracting to hear basic info being mutilated.
I think we don't have to worry about a commentator putting people on blast or anything because these guys are all smart enough to recognize that this is EVO and it's not the time to push agendas.
With that said, I think a player not competing counts in his favor, since it means no distractions/potential emo-ness. 16 Bit has that going for him in addition to his knowledge of the game, the players, and the mindset of a competitor (probably the element I enjoy the most about his commentary).
I thought Pig was great at CEO and I'd love to see him on commentary. Him and 16 Bit would probably be the best combination provided they work well together without stepping on each other's toes. I think that's one aspect that is overlooked, and why a team like Bit and Brady wouldn't necessarily work, and why Ultra David with one of these guys would work better. Now, I don't necessarily think Ultra David is god's gift to commentary the way he's often portrayed, but he does know when to let the other guy take over and do "color commentary" while he does "play-by-play." I remember when Pig and 16 Bit did commentary for the EVO team battle in 2012 and they worked together great so that's why I'm confident it won't be a mess.
I actually love Brady's commentary for MLG (and hate it for anything else) and I'm guessing he'd bring that same version of his commentary to EVO, but the other guy will not get a word in. This worked for MLG because he was commentating with Juicebox who knew nothing about MK9 and Brady had to carry the commentary on his own, but if he's commentating with someone who knows the game, it might be a bit of a Brady-overload.
Anyway, I think it's a given that Ultra David and Godspeed will do commentary at some point because of politics, but I hope to god it won't be that combination for top 8, even though it likely will be (like I said UD is a perfectly fine commentator. Godspeed, not so much).
PS: I think Kitana Prime is a very underrated commentator but he might be a bit too chill.