Best Investment of money on owner occupied

[Thomas Kelly IV]

So now that I am finally in and settled generating passive income in my first owner occupied property, now I seek wisdom.  What is the best investment of my money?  Pay off my mortgage? (My rate is only 3.25 after streamline refinance).  I have beautifully updated up and downstairs, and am going to wrap up the outdoor landscaping minimally in springtime.  So once again, do I continue to invest in solar to minimize monthly outgoing expenditures?  I am also considering geothermal heating/ac when my furnace does go eventually.  Just didn't know if my mortgage payoff should be my main focus right now, and I would like other opinions.  Keep in mind I have a 10 year plan to be moved on to my next after this one.  (Preferably another 2-4 unit next, or my dream home).  And this is all tenative, could be sooner.  Also my bills, taxes and utilities for this property are what I would consider very cheap.