I use TPS medium rings steel. Different people say different things, but unless it's just junk machined by monkeys, which you would pretty much have to go out of your way to do with current shop set-ups, if it's steel rings on a real picatinny rail, it's going to be fine. I have an LRB M25 and I think if I kicked my scope it would probably retain zero...
You can save weight using aluminum rings, but I don't trust myself and you should get a torque wrench to make sure you don't put too much pressure and bend or snap them. It's just one more thing to worry about. If you're going hunting with it, however, this might be more of an issue, as steel rings can weight literally >1 pound.
I went medium height because it allows for a larger scope, though at extreme range differences, there's going to be a moving zero of course. Also, some rings are so low and the scopes such that you have to remove the rear iron sight, which I also didn't want to do.