I have some 3M 30db passive (non-electronic) muffs, Howard Leight Impact Pros (30db attenuation but with electronic noise cancelling to allow you to carry on conversation and hear ambient sounds, yet filter out loud sounds like gunfire), and Walker Razor Slims (23 db attenuation and with the electronics).
My favorites to wear are in the following order:
1. Walkers if 23 db is enough attenuation (or with plugs added if I need more attenuation) -- because they are more comfortable, and they don't interfere with the stocks of long guns nearly as much
2. Howard Leight Impact Pro if I need more attenuation than the Walkers provide (loud centerfire handguns or rifles)
3. 3M Peltor 30 db attenuation non-electronic are obviously good for hearing protection, but I much prefer the electronic noise cancelling technology that eliminates the sensation of having my ears sealed off, so I rarely use the 3M passive muffs for shooting.