More options are almost always better. This applies to your AR-15 which, being a modular and well loved firearm in a free market, has plenty of options. One option that should not be overlooked due to its usefulness is the ability to change its size. Being able to make your rifle smaller (for range of movement) or larger (for more comfort and accuracy) can be quite useful. Folding and telescoping stocks are a great way to have some flexibility when it comes to your firearms.
Folding stocks were first on the scene, showing up earlier than the first World War. They allow for the ease of use and accuracy of using a stock, with the convenience and smaller size of having a shorter firearm. Folding stocks can be very simple, just a bar on a hinge, or they can have more options like adjustable settings. Some folding stocks are a full buttstock, others are like that bar on a hinge, literally a simple metal bar. It depends on what you are looking for as to which works best for you. The simple bar is great for weight and bulk savings, whereas the full stock can give you more.
You don’t see a lot of folding stocks on AR-15’s these days, however, telescoping stocks are very common. They tend to be easier to use, and more adjustable, however they do not usually reduce the overall size of the weapon quite as much. For most AR-15 owners, in most situations, it works well enough. It is better than the folding version in the sense that the stock simply changes sizes, rather than moving itself to a different place.
The telescoping stock is a newer technology and a little more convenient. Though the folding stock may have more benefits, the telescoping stock adjusts with the quick press of a button. The telescoping stock works well with a buffer system, though there are folding stock adapters for buffer system rifles like the AR-15. They can shorten or lengthen in a fine-tuned way, becoming perfect for the length of pull. These can give you the best of both worlds, giving you both a folding stock and a telescoping stock.
If you want a folding stock on your AR-15 you can have it pretty easily. There are these Sylvan Arms Gen 3 AR-15 Folding Stock Adapters that allow you to use a telescoping stock as a folding stock. This allows you to significantly reduce the length of your rifle. If you’re looking to pack up your rifle conveniently and easily, for stowing and travel this can be a great option. It is great for compacting your AR-15 to a smaller space, to move it. It is important to note that you cannot fire your rifle when it is folded.