Reaper
Reaper is a commerical Digital Audio Workstation made by Cockos Inc. It is know for its custimization, nagware monetization system, and low cost to own.
Pros:
*Easy precise audio editing
*Effects are non-destructive
*Can use vst plugin software to expand it capability
*Low cost to own if you choose to purchase.
*Can import and export lots of formats
*Very light software
Cons:
*Poor user interface
*Built in effects are limited
*Can be overwelming for beginners.