Sounds like you have a wealth of choices for antagonists, then. It might be harder to choose which angle you want to go at it from.

I have some people I could use, but it's not them so much as the system they represent that's really standing against my main character. I might just write about the system, but it'll probably be more effective to write it about the character who personifies it for my protagonist.

I'll probably try a few different ways.