Why don't more people use throat mics?

It's probably because people you are talking to are nice. It's a bit awkward to ask someone to invest a little in a better mic.

I did complain however to a colleague that his room is somehow generating a low-end feedback or standing wave. I measured the peak frequency and asked him to measure his room, but I couldn't confirm 100% if that's the reason :) Probably nobody else noticed it, it just annoyed me because I have studio monitors, I had to unplug them to understand him better.

If you are curious if it really has good audio quality, render a spectrogram of the throat mic and a professional podcasting mic and compare the image. The richer the image, the better it is.

You want it to be off camera. This means that a dynamic broadcast microphone is not a good choice. However, a condenser microphone might still work. They do pick up a lot of room noise, though.

For your requirements (which you might want to reconsider), the usual choices would be:

- A shotgun mic directed at your mouth from outside the camera. For example, the Sennheiser MKH 416 is often used ($800-$1000), the Rode NTG5 would be a cheaper but still expensive option.

- A hidden or hard to spot Lavalier microphone. These are the little microphones you see on TV that are clipped to the clothes. Good ones are rather expensive, too.

That being said, if it is for Skype calls, then I wouldn't recommend spending more than about $100-$150 on a mic, and I'd recommend either a dynamic microphone or a condenser microphone and getting as close to it as possible. I used a Rode M3 outside the camera angle for a long time and it had quite good quality, although spoken voice is certainly not it's primary use.

If you want higher quality, then you really need to say more about the purpose, your budget, and the room situation. Some reporters used to literally speak their voiceovers inside a closet full of clothes, which makes for excellent echo cancellation. Even a very cheap microphone can sound excellent without background noise and without room reverb (or in a room with good natural reverb).

Since you ask "best sounding" by the way: At a certain level this also depends a lot on your voice. The same mic can flatter one speaker's voice and make another speaker's voice sound ugly.

Final advice: Microphones are similar to headphones. Below $80 most of the stuff is crap. There are a few exceptions but be careful. Then there is a mid category between $100 to $300 that is a sort of sweet spot for non-professional users, and above that prices go up indefinitely. Once you know your price range and requirements, you can find some more affordable and even better alternatives to the well-known brands and choices with a bit of research, but you generally get what you pay for.

I considered making a box that accepts inputs from dynamic mics, adds some warmth, and has a USB output, to make it easier to get the LDC sound from something like an SM58, but I think nobody would buy it.