I have an LMT SOPMOD stock on my recce rifle (SPR, but with 16" barrel rather than 18") and it get's my vote. At about $200 for the kit, it's not cheap, but it locks up just as tight as a CTR stock on the LMT reciever extension and has the extra storage of the VLTOR stock.
I've used all 3 on this rifle and prefer the SOPMOD. It is VERY sturdy, and is very streamlined. It was designed by NSWC CRANE (the Design center and purchasing agent for Naval surface warfare technology) for Navy carbines, and is now the stock issued with M4A1 (SOPMOD 2) and Mk18 carbines and the Mk14 for SOCOM. The Army also issues them on M4 carbines.
For an SPR, the CTR was too small and too light. I'd recommend it for an SBR carbine but not a long gun like the SPR.
The E Mod was very nice, locked up tight, and is a good value. It is longer and heavier than the other 2, though.
It's all personal choice, but those are my preferences. What you need to do is outline what features you desire in a stock and pick the one that suits your needs best.