Discover is a good start, they can be fairly generous with CLIs and seem to like usage. As for Capital One... if you just want to "get a foot in the door" with them, I'd personally rather go for a Platinum than pay the AF on the QS1, but if you qualify for those two and feel lucky you could bite the bullet and just app for the regular QS without the AF and see what happens. Or you could just wait for a couple of statements from Discover to post and see if you get better pre-quals with them. BofA also doesn't seem to spooked by thin files, but their pre-quals aren't that reliable so it's up to how adventurous you feel. If one of the Amex cards you're prequaled for works for you they're also a good shot as they can grow fairly quickly.
Chase might be a no-go for up to a year as that's what they like to see in terms of history before giving you a card (as always YMMV). Either way, now that you have started a profile of your own with the Discover your pre-quals should also improve as your statements post as now you'll actually have a proper file to be pre-qualled off of. Good luck!
