Back in 2011 I created my own player rating system to help me better understand Major League Soccer. The purpose wasn't intended to tell me the difference between the 45th best player and the 57th but to give me an idea of who was in top quarter, top half, bottom half. Stuff like that. It also serves to keep me close to some of the more basic (tried and true) stats.
As time has gone by, Castrol Index, Squawka and WhoScored.com have joined in. Each of them have wonderful systems but I'll put mine up against theirs any day of the week!