There are a lot of oppinons about this.
For 36 years, I have used two wax rings.
One with a horn, layed on top of a wax ring without the horn.
We install hundreds of toilets a year, and sell hundreds.
We offer a one year warranty on our work.
That's what we do, and also our customers that can follow instructions.
You can also look at the Fluidmaster waxless seal.
Those work nice too.
I'm not a fan of adding spacers.
Unless they are sealed, it's just another place to leak.