There are two considerations to consider when getting a clarinet swab: material and shape.
There are four main materials available for clarinet swabs:
Silk
Cotton
Chamois
Microfiber
Every one of these is adequate for swabbing condensation from the clarinet bore. However:
Chamois is thick, and swells when wet, making it easy to get stuck in the bore. (It also doesn't launder well.)
Cotton cloth is good, but also easy to get stuck, and if there's a tear in the cloth that you don't know about, it's VERY easy to get it snagged on the register tube.
Microfiber doesn't swell when it gets wet, but it doesn't compress well either, ergo it's easier to get stuck.
All of these materials work okay to remove moisture, some a bit better than others, but the risks of getting them stuck in your bore vary.
If you use chamois, cotton, or microfiber, you have to be very careful that the swab doesn't get bunched up as you pull it through the bore. This happens particularly often when you swab from the bell. Once you get any of them stuck, you're sunk.
If you use chamois, cotton, or microfiber, when you swab from the upper end, you have to be very careful that the swab doesn't get stuck on the register tube.
Silk doesn't expand or compress, so if you swab correctly from either end, you'll be okay. It's very difficult to get silk bunched up enough to get it stuck.
The shape of the swab matters a lot, also! Swabs generally come in three shapes:
Square or rectangular
Triangular
Elliptical (tapering off at each end)
Square, rectangular, and triangular are easier to get stuck than elliptical.
If you use silk, you'll almost have to try to get the swab stuck. (I never have, nor have I ever seen it happen.)
All of my swabs are silk, made by Doctors Products, but they aren't available anymore, so the swabs that I have experience with and that I recommend are:
The Protec 3-in-1 or their standard version
The BG swab (microfiber, but at least elliptical)
The GEM swab (square, but silk)
A few points while I'm here:
NEVER use your swab to clean the tenons or sockets on your clarinet! You'll get dirt and cork grease on it that will transfer to the bore when you swab. Use a paper towel or a piece of cloth.
NEVER buy a swab with a metal weight and-or chain. (Do I need to say why?)
DO swab from both ends, not just one. If you swab from the bell only, moisture upside of the register tube might not be removed.
There's nothing wrong with swabbing your mouthpiece! (Don't let "experts" tell you that swabbing screws up the mouthpiece bore. Entirely unproven.)
Had enough? I thought so.
Adios!