I knew I would be too late... either way, I can't help but comment on it - even if you've chosen a definitive cover - great stuff here, ABC!
But honestly, for the main cover, I think the very first picture you posted is (was?) the best. The plain black background keeps it clean, with the Executor "hovering" just above the title logo - very imposing. It's clean, dark, gray and colorless, almost sterile - exactly what the Empire represents. And since the Empire steals the show in TESB, maybe it's best fitting thematically...
Plus, I have to admit, it makes the Audophile Edition more like a CE/SE than a regular OST release. Every special/collector's edition soundtrack or game I have seem to use a clean, stylized cover with as few decorations as possible. IMHO, this is again the best fit.
Don't get me wrong, I'm not complaining. Whatever you release, someone amongst my friends with knowledge about three-folding disk cases and laser printer is about to get very bothered... mwa-ha-ha-ha! >:D