I'm surprised no one has mentioned the Larue FUG, my personal favorite. It has Larues QD hardware, can be changed to three different lengths/styles and has internal storage. I've had a few different models of VFG( MAGPUL, Troy, Mako) and tried numerous others and the Larue is definitely my favorite. It just feels great in my hand and I
really like the option to switch sizes from a stubby to a full size to a full size with a wide endcap. I regularly switch between stubby and standard full size unsure of which is my favorite
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I like QD hardware on most anything that attaches to a picatinny rail and can definitely see where having a QD VFG in a battle rifle or SHTF rifle could be useful, mainly in case you need to rest the forend on something and the VFG gets in the way or forces the rifle to sit too high. Of course a situation like that is unlikely for the vast majority of users but let's be honest, many of us set up rifles for a situation we have no chance of ever being in, combat
. The Larue QD is super fast to install/remove and locks down very solidly. Their QD hardware is up there with the best.
Yes, the FUG is expensive but most nice things are....also worth noting Larue includes a lot of cool extras(meat seasoning, AKA "Dillo Dust", an armadillo shaped bottle can opener, bumper stickers etc)
http://www.laruetactical.com/lt-fug-forward-universal-grip