Good external USB mic

Lestratcaster

Dropped my iRig Studio mic on the floor earlier, the mesh covering has broken and although it still works it won't be long til it dies so I'm looking around for a new one.

The Audio Technica ones look good, but have also seen the Blue Yetti ones. Just need a USB type one mainly for Skype calls, and as a guitar teacher I record lesson clips using my iPad as the in-built ones are crap as we all know.

Any good recommendations?