If it's a bearing:
Nylon can be a great choice. It's tough got a low coefficient of friction and tolerates moderate heat. I think the reason we see so many bearings from nylon is it's cheap and flexible. There are better choices though.
Delrin is nice for low load low speed because it's cheap easy to machine and pretty tough.
If it's a high pressure bearing or expected to last a long time, I'd consider Rulon LR. Rulon uses PTFE as a precursor. If it is really heavy loads look for Rulon 142. If it's food safe you want, try Rulon 641. If the bearing is going to impinge on a gummy material like Aluminum then Rulon J is good. I've made a lot of bearings from Rulon when I was in the aerospace R&D business.
UHMWPE is a great light duty bearing material too; Machines like Buttah'
Nylon is often most often used as a bearing material when molded. Nylon 6 has graphite in it.