I used to use the Howard Leight Impact Sport but I found them to be too big for my head and the earcups wouldn't get a very good seal, and that was bad for me when im trying not to go deaf.
Anyway, im am now using the Pro Ears Predator Gold. I like these much better, the sound quality is better, the NRR is 25 compared to 22 for the Impact Sports, the Pro Ears are scalloped and don't get in the way when im shooting my rifle, and you can actually hear where sounds are coming from. I had my brother wearing my Howard Leights once and I was wearing my pro ears and he heard a motorcycle and that they might drive in front of us. I asked him what he was doing because I could hear the motorcycles as well, except I knew they were coming from the highway behind us. It really does make a difference.
The only downside is the price. I got mine on sale for around $210.00 but I see them commonly sold for around $280.00. But hey, they work real well. The Predators are made for people with smaller heads (like me), the Stalkers are very similar (scalloped as well) and are for folks with normal heads. They also make a model called the Pro Tac Slim with an NRR of 28, but have a profile similar to the Howard Leights that you may not like.
I still double plug, even with these high dollar earmuffs. I REALLY don't want to lose my hearing as a result of my hobby, so I bought the best (to me), but to each his own, I know they are expensive.