I use ear plugs called 'Earpro Sonic Defenders' by Surefire. They are soft, very comfortable and seal really well in my ears. I've had custom molded plugs that don't come close to these. They retail at Brownells for about $14.
http://www.brownells.com/.aspx/pid=23976/Product/EARPRO_SONIC_DEFENDERS
I like earplugs because:
- ear muffs push in on the glasses on the temple and over time cause me headaches
- ear muffs, on a warm day, get really hot
- when I mount a rifle or shotgun, the butt stock and ear muffs interfere with each other
The custom molded plugs I have, when mounting a shotgun, the seal in my ear breaks. These EarPro ones are soft and flexible enough that the seal doesn't break.
I like these plugs so much I have a few sets of them, one for my range bag, one for the car, one for the motorcycle and an extra set incase I loose one.