I guess my interests are pretty diverse, too.
When I finish anything, I build mostly military subjects: Airplanes in 1/48 and 1/72, though I have some 1/32s in the stash; ships, mostly USN, in 1/700, and various navies, in 1/1200; not much armor, this time around, though I built more of it when I was a kid, mostly Monogram's 1/32 series, reading Shep's excellent and inspiring "Tips on Building Dioramas".
But I also build sci-fi, specifically, Maschinen Krieger. A buddy got me hooked on them, and now a sub-stash of the main stash contains about 30 MaK kits.
And I have a collection of resin anime girl kits, in 1/8 or 1/6 scale.
But I also cast and paint toy soldiers, mostly 54mm, and mostly Seven Years War or Imperial German Army. In fact, it was through toy soldiers that I made the journey, after giving up building models when I graduated from high school, back to scale modeling about 10 years later.
I have also built one car, in that time, and have another one in the stash. I'm not that much of a car fan, whether in kit form or in 1:1, but I also believe that a good modeler should be able to build a kit of any subject, whether he likes it or not, and I got those cars through our club raffle. And they were fun, and I do have immense respect for the guys who achieve a showroom finish, or who are masters of the junkyard style of finish. I can look at any build, and appreciate the work the modeler did. None of this, "car guys vs armor guys vs airplane guys, etc, etc" for me. We're all part of the same hobby.