The best plugs are those you personally are comfortable enough to wear often enough to make a differance.
For me that is the CaboFlex that Brian pictured. Another up side to them is not handling the ear insert, jsut the band. Also, the slick, impermeable foam that doesn't pickup or hold most 'dirts' etc.
The downside is the way the can stethescope sound through them. So, may plot to have band on back of head or under chin, where ever to avoid contact vibrations IMLHO. i've only broken a few bands over the years, a place that sells to the city locally even sells them/ has them and the pods on the shelf.