This is because tabby is actually a *pattern*, not a color. It's characterized by stripes, swirls, and spots, and can come in a variety of colors like black, brown, orange, and even silver.
While tabby is the most popular pattern, black is often considered the most popular *color* for cats.
Ultimately, popularity can vary depending on location and personal preference. But tabby and black are certainly among the most common and beloved cat colors!