While GarbageBand and BandLab have editing features, they are limited in terms of functionality. WavePad offers more advanced audio editing features for those looking for the best audio quality possible.
WavePad is free with limited features and they also offer a professional version that costs $60.
Luckily, all the audio editing tools necessary for a great sounding podcast are available in the free version. This includes cut, copy, paste, insert, silence, auto-trim, compression, and pitch shifting to just name a few.