That's not a question that can be answered that easily. You might choose to get both matte and gloss versions of each; most of us probably have both matte and gloss paints, and probably have a mix of enamels and acrylics and even oils.
You could buy all matte acrylic colors, too, and use a gloss coat, whether Future, or a purpose-made modeling gloss coat, to provide a gloss finish as necessary.
When I started out building models as a kid, I started with Testor's gloss enamels in the little square bottles (I still have some bottles from back then, and the paints are still good). As I went along and learned more techniques, I bought matte colors, both in bottles and in rattlecans; I built military aircraft, ships and armor. I got back into modeling about 10 years ago, picking up the same subjects.
In the meantime, I also took up casting, painting and collecting toy soldiers, which I paint in gloss finishes. I still use both matte and gloss paints on those, choosing a paint for its color so I don't have to mix a color, and then I seal everything with a gloss coat (Future, since it's far cheaper by volume than purpose-made gloss coats).
I also have a selection of artist's oils in tubes, which I got from an artist's supply store (Dick Blick), because oils are the traditional medium for figure painters. And I've bought the cheap craft store acrylics, well, because they're cheap, and I've experimented with those (one lesson I learned is that the pigments used are too coarsely ground to get a really smooth finish, so I'm careful about applying them, depending on the subject. But they make great washes).
I have a set of pastel chalks, too, that I picked up to use for weathering. Other guys buy commercially-prepared pigments that are basically the same thing, with some binding agents added. I prefer to buy the chalks and grind them myself.
So there's no one-size-fits-all, per se. You mentioned that you've got NASCAR kits. I know some car builders who buy the actual stock lacquers from automotive supply shops, and use those on their car kits. Others use Rustoleum and Krylon and other hardware store paints, for subjects like those. You'll probably experiment, even if you use our advice as a starting point, and find what works best for you, as you go.
Hope that helps!
