For example, you take horizontal photos of spaces that are tall and narrow, so you should have shot them vertically.

As you mention may want to look at dividing the space and trying to get two tenants in there

And are potential guests interested in staying at a STR in a basement that can have occasional squeaky floors from time to time?

Some owners would prefer a clearly defined floor even at the cost of not rising to the highest ceiling.While I hate to say it, there are also property owners who lack either the time, knowledge, inclination, or skill to want to manage their property effectively.

I just feel that I can't pick a winner in this space confidently right now. 

I would base your answer on buying the bigger one (within reason) that will fit in your space that fits your budget.  

Consider creative approaches like short-term rentals, ADUs, or co-living spaces that maximize income in limited spaces.

But they asked for a little space to store their Christmas items. 

I know very little about legal precedent but I'd expect the major meter manufactures (selling into the utility space) to be well incentived to challenge these items best they can, and they have money.Here are the issues, and the reasons that the difference between an air forced system and a boiler/hydronic system are not meaningful for this discussion (ie efficacy issues of sub metering exist for either when method of measurement is measuring heat at point of delivery):In either case, the blower (or pump for a boiler) is the method of 'moving' either air (central air) or water/glycol or equivalent (boiler etc). 

Updated kitchen but I’ll need to do floors and update bathrooms.