How much weight are you willing to carry??
I use a standard Gamechanger when weight's not a concern:
https://www.armageddongear.com/Game-Changer®_p_111.html
You can get a pint sized and save some weight/bulk or go with Git-lite fill ($$)
When weight/space is a premium, I use a Thunderbird Long Range, Mini-Tacky with Git-Lite fill. I use this for both a rear bag and I've been using it on a ball head.
http://thunderbirdlongrange.com/store/p13/minitacky.html
I'm really, really liking the Mini, it's easily strapped to my pack and still does a good job.