tuffy:
Although you only list the above two, you might also want to add a third to your list, that, to me, combines the best of both worlds of the Q-Claw and the Joe Porper cue holders.
It's "The Gripper" by Bauer Enterprises:
http://gripperbybauer.com/
...and its matching carrying strap:
http://gripperbybauer.com/viewItem.php?id=8
It combines the weighted rubber idea of the Q-Claw, with the greater cue-holding ability of the Joe Porper. It's even designed to hold rifles and shotguns, that's how secure its cue-holding ability is! What's really nice about The Gripper, is the material it's made of -- a very tacky rubber compound that really grabs surfaces (even on an incline) but doesn't attract dust or dirt. And the channels that are cut/molded into The Gripper are extremely deep -- much, much deeper than the Q-Claw, and actually will hold an "over-and-under" (double-barreled) shotgun all the way to the second (lower) barrel! The pics on the website above show this.
I purchased mine last year, and I absolutely love it. Had the Q-Claw, and and disliked it because the channels are not cut deep enough (was very easy to knock a cue out of it). I ended up giving my Q-Claw away as a gift to a person I was introducing to pool.
Hope this is helpful!
-Sean