The answer is still basketball. Just as a hypothetical example, let's just say UK wins a football championship this year or next. Then what happens? Stoops likely gets poached by a 'football school' and it's back to years of finding the next Stoops. And whatever bump in money and recruiting will be gone in a few short years. Do you want to be the hands down GOAT in basketball and mediocre/competitive in football, or do you want to be elite in basketball and still mediocre/competitive in football again? Sure a football championship would be a blast, but basketball is what butters Kentucky's bread.
We can financially compete with anyone to keep Stoops here. We have top 25 fan support with a program that has been considered a joke for decades. We already play in the premier college football conference. Our facilities (outside of our indoor practice facility) are better than most of the traditional powers. Stoops has an amazing contract here with far more lenient expectations. It has given him time to slowly implement a working strategy. We were never going to win the SEC overnight from the pit we lived in for 40 years.
There are really only two reasons we're not already a "football school". A poor reputation/tradition that haunts us due to decades of negligence, and weak in-state talent, which can be nullified by being Ohio's path to the SEC (like Stoops is doing).
Most of the ingredients are there for us to be every bit of the football school that any other SEC school is. It just needs time to cook. A football title would advance us ten years overnight. Only four schools have won the title in the CFP era: Ohio State, Clemson, Bama, and LSU. That's it.
Plus it's not like we won't literally always be in the hunt for a basketball title.