What do you find the best in after market stocks? What have you found to be the best in both collapsible and non-collapsible stocks? Ace, Vltor, 4 position, 6 position, etc?

Go A1, A2, or ACE.   The telestocks I have seen (especially the aluminum 2 position one I own) are loose and don't feel quite right.  Your mileage may vary...

You can find some good stuff at gun shows.  I got a nearly new modern production (grey, not gloss black) Colt A1 that was in a pile of $10 '60s era beaten A1 stocks at a gun show.  I assume it was removed for a telestock, then lost into the junk piles.