I'm not all that sure about who does and doesn't have a quick release, or who goes through his progressions better than whom, but from what I see, EJ Manuel is a keeper.
Having already used a fishing term ("keeper") I might as well extend the metaphor. I fish a lot (too much) and whenever I do, I reach into my tackle box for the lure I have the most confidence in.
It may not wiggle the best, or glow the brightest, or have the quickest release, or go through progressions more smoothly than some of the others, but it lends me the most confidence that I will somehow succeed.
That's what EJ Manuel does for the Buffalo Bills offense.