There are many people out there who will tell you XLR mics are better than USB. These people will tell you there is a big difference between the two. Sure, if we A/B test different USB and XLR mics there will be a difference between a Shure SM7B and a Samson Q2U, but is this difference because of the type of connector? Are we even able to make an accurate comparision? Not really. Let's talk about why.
An SM7B will generally sound better than a Samson Q2U, but it's not because it's an XLR mic. It's because the SM7B is simply a better mic. If we compare the two, we are hearing differences between the mics, the preamps, and the A/D conversion. So, we're not only comparing mics, we're also comparing the Q2U's built-in electronics to the interface being used to connect the SM7B. If we plug the Q2U into the same interface we're using with the SM7B, is the Q2U going to instantly sound better? Maybe slightly. There might be less noise due to a cleaner preamp and better conversion, but very few people will hear this once the audio has been cleaned up, mixed, and converted to mp3. As I said before, the difference is due to one being a better mic than the other. If Shure made the SM7B availble with a USB port, it will still sound better than most other USB mics simply because it's a better mic. It's nothing to do with the connector.
To exemplify this, I put together a blind listening test with 7 produced clips. Some were recorded with XLR mics and some with USB. The point is to see if you can even identify which mics are USB and which are XLR. If you can't, then there isn't an "audio quality" reason for choosing one over the other. Choose the best mic you can tht fits your budget and your needs. If you're recording by yourself or conducting remote interviews, you don't need a Rodecaster Pro. It's simply overkill and adds complexity to your setup.A good mic with both USB and XLR connectors is a good place to start. Plug and play simplicity with the ability to grow with you as a podcaster.
As a podcast editor, it's important that we truly understand the difference's here if we're going to be able to help our clients. This is one of the things that baffles me about the Podcast Editor's Group on Facebook. We aren't allowed to talk about microphones or the merits of USB mics. It's shunned and any post that touches on the topic gets removed. Here at Tansy Aster Academy, we welcome all conversations about equipment, production, content creation, and editing.