Water based lubricants are the most versatile, popular, and readily available lubricant option. These lubricants can vary in texture from thick to watery, can be used with condoms, toys, and (as long as the ingredients are safe) part of the body. Water based lubes are the jack of all trades of the lube world.
The downside of water based lubricants is right there in the name: they are water based. The water in them evaporates with use causing them to dry out or get sticky. Many can become slick again with the addition of a little water but this is still considered a downside for many users.