For me, frameless packs are a very different animal compared to framed packs. The comfort of a pack being something that can make or break a trip (or the backpacking experience as a whole) makes pack selection uber important.
Though I have never tried any of the packs you've listed, they are all well received on BPL. What it comes down to is comfort, comfort, comfort, and that's the tough thing about trying some cottage gear.
I'd recommend, as Douglas pointed out, to try and dial in the rest of your kit. Then you'll know how much space you'll need in a pack, how much weight you'll be carrying, and what features you might want.
If at all possible, try to find a gear retailer near you that sells frameless packs, and has a good return policy. While I do not advocate taking advantage of fantastic return policies like REI's, I personally think its ok to try something out as long as it sees minimal use and absolutely no damage. Gotta bring it back like new. Anyways, get a frameless pack, load it up at home and wear it around the house. Or maybe take it for a walk down some trails--again, being careful to keep the pack in a new, returnable condition.
You'll see pretty quickly if frameless packs are for you. There is something to be said for the suspension of framed packs, even though they weigh more. If a 20 oz. frameless pack feels more uncomfortable than a 3 lb framed pack, then there's nothing wrong with the framed pack. In fact, you'll probably enjoy backpacking more. And it is also entirely possible that you can put together a super light kit and thoroughly enjoy a frameless pack.