in my case i prefer neckband earplugs (the one on the right).. reason ? I currently work in Line Maintenance.. this gives me the freedom to simply put it in when I'm on the ramp, and also the freedom to just remove it and let it rest on my neck when i have to go to the cockpit or cabin.
And its actually quite good at removing or lessening those high pitched noised that irritates most of us..
http://4.bp.*************/_WVvU9V5zI...-R/earplug.jpg