Most people are using cameras that require lenses. Lenses are going to be the most expensive investment.... But if you pick a brand (Canon, Panasonic, Sony) then you can use those lenses on most cameras... if they have the same mount.
Pick a brand, and then base your lenses around that.
I use the Panasonic GH4 which uses M 4/3 lens mounts. I also have an adapter for Canon lenses.