As you can see from @Mike9241 's detailed response, qualifying as an RE professional is not simple for those who own 1-3 rental properties while working a W-2 job. If you've been on SCH E for the last 10 years, there's really no benefit I can see to changing anything.
As it stands, if you can meet the 250 hour rule then you might qualify for the QBI deduction. If you don't qualify for the QBI deduction on SCH E now, then you won't qualify by changing your rentals to a SCH C business either.
Some other stuff that may or may not apply to your specific situation.
Rental property in general produces passive income. That's why it's reported on SCH E and is not subject to the additional 15.3% Self-Employment tax.. The SCH C is used for "earned" income and that income "is" subject to the additional 15.3% self-employment tax.
I've seen instances where people put their rental property in an LLC only to find out they are "still" required to report it on SCH E. Thus, they don't have a single penny of "earned" income to report on SCH C. It really throws them for a loop when they discover this the hard way.
Now I'm not saying you can't report on SCH C (if you qualify). What I"m saying is that you need to determine if it's really worth it, and ask yourself "what do I gain by reporting as a SCH C business?"
If you qualify and decide to go the SCH C route, then understand it's not a simple matter of just moving all the data to SCH C. It's quite a bit more involved than that, and will require a lot of manual math on your part. One tiny mistake can cost you dearly years down the road too.
