I use the Peltor Tactical Sport (model MT16H210F) and am pretty happy with them.
They are a fairly low profile electronic muff that only slightly interfere with rifle/shotgun cheek weld. They use AAA batts, which I have yet to change after 3 years. Comfortable, I've worn them for hours while driving my tractor.
They are 20dB rated, but at times at indoor ranges, I think better sound isolation would be advantageous. When shooting outside though, they are great. I love the way they amplify the low level sounds. Very strange to hear your brass hit the concrete after the shot! Conversation level noise sounds like not wearing hearing protection.
I typically have to keep my eyeglasses on the outside of the muff as going between the ear pad and my head causes sound leaks.