...in shooting muffs is the pair which reduces noise the best. In this case more $$$ mean more protection.
I have two pairs which are excellent, but they aren't cheap.
The best I've found (and now use exclusively), is the Magnum Pro Ears Gold. There are none better.
Second is the pair made by Peltor, the Tactical Pro.
Neither of these are cheap, but they work the best of any out there.
I also wear custom-molded plugs at the same time.
Here's a link to NIOSHA. They have a site devoted to hearing protection. They also have a listing which gives the cost, and protection levels:
CDC - Noise and Hearing Loss Prevention - NIOSH Workplace Safety and Health Topic