OK, I reviewed the few archived posts I could find on on this topic ...
The Tango Down grip is my pick at this time.
For my purposes, the excellent CQD offering is overkill and the higher price point -- about double the Tango Down, IIRC -- is more than I want to spend.
Can't seem to find the Knight's grip for sale, and it does not seem to be vastly superior to the Tango Down anyway, from the little bit I read.
Any other vertical foregrips I should consider?
Thanks in advance for your guidance,
I like the Knights grip.
It came with my RAS II. It easily attaches and detaches from the rail. It hasn't broken yet.
It doesn't house a spare bolt. I don't need a spare bolt on my rifle. I'm not going to be changing bolt in the middle of a fight.
Buy whichever one is cheapest, and looks comfortable.
Keep your eye on the EE. Lots of KAC (Knight's) grips for sale there. Most go for around $25. If you want 'storage', GG&G sells a replacement core that fits the KAC, IIRC.....or just get the GG&G grip. See those once in a while on the EE as well. My A4gery wears one, and it works just fine for me. Holds two spare SF123's for my light.