When you're looking to make a cross that'll show quick results, you'll want to take these two things into consideration: the plant and how well you can grow it. The plant bit's common sense, just don't get something that'll take forever to flower. As far as culture goes, also pretty simple. The better you grow it, the sonner it'll flower.
I've heard that phrags and masdies can flower quite soon from flask (2 years). To me, the masdies taking less time to bloom makes more sense, them being pretty small plants they don't need to build up much plant size before they bloom.
The following is just speculation, but you might want to look at some of the twig epiphytes; the really small plants that live right on the tips of the branches in nature. I've read that because it's such an unstable environment on the edge of the trees, that they have quite a fast life cycle so they can germinate, grow, and reproduce before they get smothered by the expanding canopy. Of course, there's also the risk of the branch just snapping off, and there's no buffer provided by the tree between them and the elements, but that's beside the point.
One important thing that's been missed is this: the time it takes to form a pod that you can actually flask and get seedlings. For vandas it can take
three years to get a mature pod (but you can probably green pod flask at two years). I wouldn't want to wait that long, and it doesn't sound like you do either.
Here's a link to a series of tables with a ton of info on how long it takes to get a pod you can flask.
Hope this helps. Whatever you choose to do, best of luck and all that.