Which stock is best is going to depend a lot on the rest of your rifle, your height, and build. I use a MagPul PRS stock on my rifle. It's fairly heavy, and balances out the rifle since I have a heavy profile fluted barrel. A few of my shorter friends don't like the length of mine because they are to small to get a good consistant cheek weld with it. If you want the adjustability of the PRS without the weight, then I like the Luth AR stocks. For carbine stocks, I really like the MagPul ACS stock.
Stocks are a very personal thing. Your best bet would be to go to a match and look at what other poeple are using. I haven't met a shooter yet that won't let me look at the gear they have. I have guys come up to me and ask about gear that I have at matches all the time. I've let a few of them shoot one or more of my guns on a stage to try it out.
That or go to a big gun shop and just look at them there. Match would be the better option to me as you can see what the stock is like with optics mounted.