@Kevin S.
First, figure out your strategy, goals, level of involvement, etc. I think further educate yourself. Trying to compare the S&P to purchasing an individual rental property, which people keep doing is ludicrous.
Hmm... Why do licenced/fiducary advisers keep recommending a broad based etf? Risk diversification, don't pick a sector, don't time the market, no leverage, etc.
However, what is real estate investing? Picking a particular sector... picking a particular market... in some ways timing the market, etc.
S&P etf isn't the only way to go. if you want income vs growth, get any of the various income producing securities or funds that have been putting out dividends for years, if not decades. Many are now doing 10% and even 12% yields. Some are even tax free. Its completely hands-off (other than monitoring your account), very liquid, no additional expenses (like a leaking toilet, new roof, new flooring, etc.), and not deferred tax liability (which automaticlaly happens with a rentla).
Oh, and you still get a step up in basis --- don't know why it keep being sold "as-if" real estate is the only asset that gets a step in basis on death... And the transfer is really easy, no probate (just assign a beneficiary), and you don't even have to re-record a deed...
But back to your question about one property all cash or leverage? Generally, if you leverage you'll have reduced cash flow. So... go back to step one and figure out your end goal. Are you really in dire need of cash/income to live on? or trying to leave a legacy?
Hope this helps. Happy to chat. Good luck.