I would prefer for Data to stay dead.
But what I would like to see is for Maddox or someone to perfect regular positronic brain technology. Then we could have the great novel writers handle the topic of artificial lifeforms. I'm sure they'll do better than the show writers from 2+ decades ago.
How do these new beings get their rights? How do they integrate into society without lossing their individuality? How would they choose to live? Who would control the "birth" of new androids as they were made? How would this affect holographic rights, etc?
So, maybe a new android character, like Data. But at his/her beginning, so we can see their struggles to understand and integrate into society from the beginning. (Of course, if this was done in a realistic manner then such a being probably wouldn't be serving on any of our Starfleet ships or bases for at least 5 years in-universe. It would take time to learn and get into Starfleet, etc. Unless they "data-dump" Data's memories of Starfleet and call it good.)
It's time for the issue of artificial beings to be really dealt with in Star Trek, not just alloded to or touched on like they did with Data or the Doctor or Vic Fontaine or the alien AIs in recent Titan novels.