At the moment I am modeling H0 standard gauge and H0n3 narrow gauge. So I voted for 'More than one HO scale gauge'.
BUT:
I started with N scale in 1970. After I had to dismantle my layout I got bitten by the narrow gauge bug and went for H0n30, scratchbuilding and track handlaying with a Maine two-footer theme. Finally I made the change to H0n3.
Besides I joined a round-robin group of 0 scale modelers, which unfortunately fizzled out in the early '80s. I still have some 0 scale material around, among them some Rivarossi kits. One of these days
I'll start a project of a small 0-6-6-0T.
And there is still some G scale stuff somewhere in the attic from a round-the-tree train when my daughter was a small kid.
So my correct answer should be: G, 0, H0, H0n3, H0n30 and N.
So Mikey, I'm also a hot candidate for the 'Too many scales and gauges' vote!
Ron