Video Commentary: With or After Gameplay?

Chaotic16

I've been poking around on Youtube for a couple days, checking out different channels for video / game commentary. I'm looking to do a series of sorts with a good friend of mine and was wondering which would be best: To capture our voice as we're playing the game, or record the game, then add commentary later as we're watching it (possibly to make it easier to edit, or so you can make it a little more enjoyable by reading a script of sorts). 

I've seen either of the methods here, but was interested in knowing what the MMORPG community preferred.