We tried many brands and styles and had varying results. This is the only one that didn't leak in the cot even after years of use with several kids. After around 3-4 years some valves did start to leak a little so we just bought a new valve. So very durable and easy to clean. Cost a little more than some others however it is the only one we kept using for years.

All parts of valve that come into contact with liquid can be directly cleaned. Doesn't leak so can leave water bottle in cot overnight. Durable and survive chewing toddlers. Good flow. My kids prefer these to other bottles and so do I. Love these! Cheap. Sometimes hard to find in the shops.
Cheap, easy to clean, don't leak, durable.
Can't think of anything. Would be good if could buy valves separately, as have lost a few.