Of course things can occasionally go wrong like a loud/drunk guest disturbing other guests but people understand the risks associated in apartment style buildings to a degree.Our very first STR was a small mansion on the beach that also had a detached 2/1 with a pool between the units. 

Did I tell you that I get to sleep with my house cleaner for free?

This site is working for you 24/7 so you can generate leads while you sleep at very low cost! 

The only thing I am hesitant about is that across the street, there is a property with a weird construction: a garage with a huge (metal) roof, which could be visually disturbing for some people.

All you need to do is beat their alternative investment rate and give them plenty of security so they sleep well.

"It's good" or "it's just hot outside" is not a satisfactory answer on how the unit is running.It is disturbing that the outside unit i.e. the condenser was replaced with a larger size but not the evaporator/air handler. 

Check the plumbing - I prefer to always run new hot/cold risers and laterals before you start renting, as it will never be an easier time and you can sleep well at night knowing there will be no calls from tenants about a water leak!

It is very hard to stay motivated when all of the other people my age are only concerned with going out to college parties, wasting money, and sleeping in all the time.

If I could flip like the re-habbers here, I would go 100% plus leverage but I don't have that skill set so that leaves me to buying-n-holding for cashflow but considering ROI I might just sleep better off in the market for the long run......For me, deflation is more dangerous than inflation. .....I got that call initially correct in 08 by liquidating my entire portfolio but made the mistake of underestimating the FEDs willingness to make us Japanese.

Assuming you're having a tough time making this decision, then just pick one and don't lose sleep over it.