Or is there some 3rd factor of overwhelming importance that matters more (besides the pathological cases, ie. if one is a shack next to a railroad depot and the other is in McMansion estates, etc).Would love some thoughts on this since my own preferences for such things are often not aligned with what popular with the masses.

Class C value add is pretty popular, I'm sure you can find the money if its a good price.

Job relocation is a popular exception, but you need to document this. 

and what amenities do you find popular that mesh well with both STRs and the Snowbirds?

It's a popular area and should be pretty easy to fill.

I do feel remorse over paying the condo off early on, just a bit of a newbie(or maybe due to following a different advice from another popular media source).

There are some nuances to it, but house hacking is by far the best and most popular way to start your real estate journey. 

That does seem to be the popular answer and lines up with what I was leaning towards too!

After the first year, this property will have a 16%+ COC ROI and it is in an extremely popular area (.5 miles from a D1 University) and the only time it's units are vacant are usually only the ~10 days it takes to get new tenants in.

That is where the market is less popular than some that come to mind instantly, but, your sweat equity and knowledge of the market will counterbalance the visibility / consistency over time.