First of all, I'd very much rather they fixed that goddarned UI, and the deal screen in particular. It's the single absolutely worst thing in this game, it's the most poor and atrocious user interface in the whole series. Civ 1 has better UI, for godsakes.
When the number of traded luxuries increases, the thought alone about the utter chore of renewals already puts me off playing. As soon as the luxuries appeared in the franchise, in Civ 3, you could see instantly if AI has a particular luxury and if it would trade it. Civ 4 has that. Civ 5 has that. So why does Civ 6 torture the player instead, making him/her leave the trade diplo screen and go to the reports screen, and go to the third tab of it, and then study the long boring spreadsheet of deals and squint at the miniature luxuries icons at the bottom, then go back to the diplomacy and make the renewal? Chances are you forget something and have to repeat it all again. No deal end reminders, remember to mouse on the gold number to see when some payment ends. What if it was a rare case of lux for lux only? Dive into the spreadsheet, Mr Accountant. And when you have lots of deals, this ritual must be done every few turns. It rather looks like bookkeeping exercise, not a strategy game.
This is the first Civ where I feel sometimes it would be nice to have an assistant to help you play, who would keep the tabs on the trade and diplomacy, and now, after the latest patch, also would remind you to appoint/promote a governor, 'cause those reminders bugged out and buggered off as well.
So for me, UI first. And only then AI, airforce, England, deployment from carriers and all other such things...