I was perusing a gun forum and stumbled across someone asking this question.
There were all sorts of answers. From people saying the old CAR stock is all you need, to people saying your stock choice depends on your optic choice. Various blanket answers like “LMT SOPMOD” or “Magpul CTR”.
Wasn’t that long ago there was only a handful of option. Now it seems like every company makes their own stocks, grips, hand guards, and the like.
At this point, it is more a matter of person preference than anything else.
Let’s take a quick look at a couple.
This is the classic “CAR” stock. Light and compact, it is my favorite collapsible stock. You could argue that it does everything you need, but it lacks many modern conveniences such as QD sling sockets or a bottom sling mount.
The M4 stock, aka a “waffle” stock moves adds a sling mount to the bottom, allowing for more traditional sling usage.
Back in the early 80s, if not even earlier, there were various designs for an improved cheekweld stock. This pretty much got finalized with the NSWC SOPMOD stock. This stock is now made by a few companies, and many other companies offer stocks with sloping sides for “improved cheekweld”. On many of these, that gives some storage space. This B5 stock, like the later LMT SOPMODs, have a QD socket in them.
Some figured that a couple of battery compartments are not enough, so they added even more storage space. Put in a cleaning kit, or extra CLP. Maybe even jam a “fun sized” Snickers bar in there. Just note that some designs, like the VLTOR stocks, can grab beards and pluck hairs.
I remember the Magpul CTR was considered a pretty big deal when it came out. It had a second lock that would eliminate all slop and wobble making it lock up like a fixed stock. All the advantages of a fixed stock, in a collapsible stock. I didn’t like it at first until I learned about the extended rubber buttpads. Now I really like it. But all of mine have worn and have plenty of slop like the old CAR and M4 stocks. If a person didn’t need the QD socket, I would suggest getting the MOE stock, which is the same profile minus the QD socket and extra friction lock.
For the bench rest or space-gun shooter, there are all manner of stocks that are extremely adjustable. While these designs vary, many of them have so much adjustment they can be custom adjusted to suit a particular shooters individual needs.
But, we shouldn’t forget fixed stocks.
There are the old M16, M16A1 stocks. The slightly longer (about 5/8 inch IIRC) A2 stock. Rarer odd ball options like the CS stock. If a person wants a fixed stock, they can find them in several lengths. “Entry” fixed stocks tend to be the shortest, and there are extensions available for those freaks out there that think an A2 stock is too short.
You can get fixed stocks like the Magpul PRS or the LMT DMR stock that are adjustable for length, cheek height and are designed to ride a rear bag.
There there are all sorts of other options like the non-stock braces, or stocks designed for non-AR weapon systems. Now that we can shoulder braces, there are some people who prefer these braces over standard stocks. That seems odd to me, but it is an option. There are shorter stocks, side folders, etc that will work with alternative recoil systems.
Some people highly recommend fixed stocks for precision rifles. Sometimes it is for the extra weight to reduce recoil, but often the argument is that wobble in the adjustable stock would adverse effect precision shooting. Personally, I’d rather have a collapsible stock as I prefer different length for different shooting positions and I like being able to reduce the length of the weapon for storage.
I think it really comes down to picking a stock that supports the sling and shooting positions you want to do and allows you to be repeatable in your head position.
And that isn’t even broaching in on the weird options like stocks made for visor use.