Want great rings (30mm or otherwise), think: APA (alloy), Badger Ordnance (steel or alloy), Nightforce Ultralights (alloy) or Seekins Precision (alloy) . There are other great rings as well, but these I've used extensively and were trouble free. In almost any caliber under .338 Lapua, alloy rings are more than strong enough to hold up.
I tend to buy any one of those brands, based on availability and by the height that best fits the scope, mount and rifle I'm trying to fit. None of these will break your bank price wise, and buying a quality product the first time will save you money and troubles in the end.