CST Mtb tubes are the standard for a decent mtb tube. They're great quality and reasonably well priced. It's always worth having a couple laying around for yourself, and for your friends who keep stealing yours. These tubes have a presta/french valve as desired by almost all.

These tubes are all standard thickness, not downhill thickness tubes (which weigh so much more!).

Sizing

We've always been a bit confused about why so many different types of tubes are offered. Tubes are made to stretch and so, unless there is a dramatic width difference, they're pretty interchangeable without detriment. A tube that is made for "up to 2.2inch" wide tyres also works well about up to 2.6" tyres. This even goes to the point of a 23c tube for road bikes can be used in a 40c gravel tyre if you need to get out of a pinch. 

We mention this because we source tubes in limited widths to suit what we believe are the most common applications of our customer. This approach allows us to save you money. The table below shows recommendations (both ours and manufacturer) of what tyre widths each model is appropriate for.