What is the smartest way to invest $100k?

[George Parker]

I have a few rentals that are cash flowing. Nothing too serious, but each month they bring in an extra ~$1k total. 

I’ve saved up an additional $100k and I want to know what the smartest play would be?

Should I pay off one of the mortgages on an existing property?

Should I buy another property? I could put the $100k down on a property I found that would then cash flow about $500/month. 

Should I hang onto the $100k and wait for the inevitable recession?

Would it be possible to find an opportunity that has the potential for even more upside and profit? If so, what should I look for and how would I find it?

I have the $$ to invest, but I wonder if there may be a better investment than increasing my cash flow by $500/month. Or maybe that is the best I could hope to get. 

Anyone with any thoughts?