[KevWind]

Understanding what the result of your trying different mics actually means, and having the echo (ie. room reflection) in all the recordings
Should be a red flag indicator ...... It's your room

As others have noted
The echo-y effect is the room not the mic.
Yes as others have noted you can get less sensitive mics and put them closer to your mouth even to the point of a headset USB mic (which are cheap on Amazon) and would probably mitigate most or the echo effect for teaching your business classes.
BUT that kinda defeats the intended purpose you stated in your title an OP "versatility" and for some music recording

Also as someone noted a square room (particularly a small 10 by 10 ) square room is the least desirable because it is one of, if not the most problematic, in terms of unwanted reflections .

So long term to get where you want to go consider the room first.
Can you at least put some absorber panels in the corners of you room mounted or portable on foot stands either in the corners or around your recording position ?

Trying to solve significant room issues with mic's is somewhat like putting a bandaid over skin cancer