In the states Black Diamond nylon STS skins
are kind of a gold standard for reliability and ease of use, but G3 makes some nice ones too. There are some other proprietary brands like K2, Dynafit, and Volkl that are probably okay, I just am not familiar with them. If you're a Euro you might come across Pomoca and Colltex.
Mohair vs. Nylon material: mohair skins are lighter, more flexible (for packing) and have better glide, but absorb water a little easier than nylon and cost more. Nylon grips better (which may not matter if you don't skin up steep pitches), repels moisture better, is stiffer (an advantage when dealing with them in high winds), heavier, and cheaper. Pick according to your needs.
I like tail hooks as a backup in case the glue fails, but they aren't strictly necessary if you aren't pushing hard or far.
I like to buy skins that are close to the width of the tails of my skis. This generally requires that you trim them (which can be tricky, but there are instructions or you can have a shop do it), but you will get coverage over all the important parts of the ski for the best traction. You can get by with narrower ones, but really, wider is better when you're on the trail. Pre-trimmed skins are available, but cost more and don't always cover the bases as well.