Okay.......so here we go.......

Easiest plug and play is a double reed timber. If you want to buy an easy to use insert for basic duck hunters, then that is the one to get for your barrels.
My second favorite is the single reed open water.
The single reed timber is 'throaty' and low, and the double reed open water takes a whole lot of air to run compared to the other three.
I'm not saying this is the case for all types of inserts, just for the ECHO's. But I will also say, that double reed timber is THE BEST plug and play insert I have ran into, and I try to run every one I can get my hands on.
Parker