When should you choose WebSockets over Long Polling for real-time updates?

Hey everyone, I'm building a new feature that needs the server to push real-time updates to the client. I'm trying to decide between WebSockets and long polling. WebSockets look like they'd be better for constant, quick updates, but long polling might be easier to get started with and works with older browsers. What have you guys found? When did you notice one was definitely better than the other for performance, how tricky it was to set up, or handling more users? Any problems to watch out for with either way?