The big question is do they keep you dry? And whether they actually do keep you dry or not depends on the quality and the material used to make them. And yes you can go for nylon fishing waders waders to make sure you keep dry within lightweight material, but they can be hot! The waders you buy should offer features.
Your fishing waders must be breathable.
The fishing waders should have neoprene socks, as they are more versatile than a bootfoot wader.
A durable wader should be as light as possible.
Unless you fish in near-freezing or sub-freezing weather frequently, there is no reason to get an insulated wader. Remember waders are not a fashion statement so make sure your wader size offers plenty of room for movement and extra clothing in cold days. Wader size is important to leave plenty of movement around the crutch area so you can negotiate river banks, fences etc without busting your seams. The most common area were waders fail is at the crutch and inner thigh, because they are to tight. You may look a bit like the Michelin man but trust me the fish won't care. When selecting wading shoes shoe size is important go up a shoe size to alow room for the thick neoprene socks, the wrong shoe size will be very uncomfortable. Make sure your waders come with a wading belt and make sure you use it as it is an important safty feature. Also a good breathable material and welded seams are also important. Most good waders are made of a 3 layer breathable material similar to Gortex and have 4 to 5 layer for the leg area. This gives you added protection from wear. Gravel guards and hooks to attach to your boot are also necessary. Most brands make good fishing waders and also have failures. So do your homework before you buy. Other considerations are a large front pocket at least one water resistant front pocket for your camera and keys. A large front pocket is a must.
D rings are also usefull to clip on your accessories such as a merino wool patch a D ring in the back is for landing nets.
So you have a choice of full chest waders and in warmer days you can roll them down to your wading belt to keep cool. Chest waders are a good choice for your first waders. Trouser waders. Remember while trouser waders can be more comfortable they do limit the depth of water you can wade. Then you have thigh waders which are popular when fly fishing small twig creeks in summer.