I feel like just squashing them together is boring. I'd rather it be named after Carl Sagan or something.

If a person, why not a name like Faraday, Newton, Einstein, Bohr, Galileo, or Confucius?

Not sure why Confucius made that list lol, but those scientists have distinct scientific things named after them. Farads, Newton's, the plethora of things for Einstein including his own unit, the Galileo mission, etc. I feel like the merger of galaxies is something that captures the interest of the public eye, so I feel like someone who captured this interest and motivated us further in space than ever before is deserving.