Man, JL with no GL is gonna be... weird.
It's gonna be really weird.
As for which Lanterns they eventually go with for GL Corps, I'm fond of the idea of having one experienced Lantern who's been serving since before MoS and one new guy. In that context, Stewart could be pretty interesting as the serious, by-the-book veteran contrasted with an off the wall rookie. I'd favor Kyle for that slot, but Guy would work as well.
The big thing for me would be getting the powers right, which means absolutely no green beams or bubbles. Every Lantern's constructs should be immediately identifiable as being theirs, even if it means you have to tweak the rules a little to allow for an acceptable level of variety. A GL should descend into battle surrounded by an army of their own design.
BTW, Hal has grown on me a little, but he's still the least interesting Lantern, barring his history with Sinestro. Just transpose that chunk of the character onto John.