Gandhi, Alexander, Montezuma, Shaka, and Genghis Khan are all pretty much staples at this point, but I personally would not be offended by their removal. I am actually quite partial to Chandragupta as an "Indian" leader, and am also glad to see a different sort of Greece under Perikles / Gorgo (though I am aware the inclusion of Macedon is a tad controversial).
My most wanted leaders to return:
Chandragupta
I far prefer Chandragupta as a leader to Gandhi, not really due to anything but personal preference. I do, however, think Chandragupta is an important historical figure and represents an era of Indian history that is very much underrepresented in media as a whole, whereas someone like Gandhi is much more well-known but fails to add as much flavour/diversity to the game. Not everyone is a fan of the "India" label for Chandragupta, which is understandable for a number of reasons, but I still would like to see his return in Civ VII and even beyond. To that end, I would be fine seeing him as either leader of India or as leader of Maurya or something of the sort in the future. Dividing India could pave way for other interesting groups like the Mughals, too.
Gilgamesh
If it's not clear, I do have some controversial or otherwise unpopular opinions about this subject. Anyway, I think Sumer as a civilization is a great inclusion, as they are one of the first, if not the first, of civilisations of human history. There are a decent number of leaders from Sumer that have good historicity, some of which have better than Gilgamesh himself, but in terms of this series I think Gilgamesh + Sumer would make a really good perennial inclusion, and I would be interested in seeing in every rendition of the main series into the near future. It could be that that arrangement replaces Babylon as a permanent fixture, which I would not particularly mind either. He could even come to serve as a sort of figurehead for the series into the immediate future, in a similar way as to how Gandhi sort of does now. Gilgamesh has a really great character in the Civ series so far, especially in Civ VI, and I certainly would be happy to see him back in the future (perhaps with some more historical UAs).
Musa I
I know very little about Malian culture or history, but I think Musa is just too cool a historical figure to exclude in the future. His Hajj and abundance of wealth were events that made a genuine impact on the Muslim world as a whole, which just speaks to his importance, and also lends itself to a very neat UA. The execution of Musa and Mali in Civ VI is especially quite good, IMO, and the playstyle that is unique to him should frankly become a staple. I also very much like his personality and overall portrayal in Civ VI, and would be interested in seeing similar sorts of things in future games.
Suleiman I
I am an unabashed fan of this man, and of course want to see his return. Plus, I think they did our boy a little dirty in Civ VI (Turkey, especially under Suleiman, was not just a country of avid conquerors, even if they were quite good at conquest!) and would like to see another try in the future that more wholly represents the cultural, economic, and legislative side of Suleiman's rule as well as the militarism. There is a lot that Suleiman offers in terms of unique gameplay ideas that I think could be really interesting to see in future installments, and I am not willing to give up on that idea quite yet.
Shaka
I think he should stay, only because I think the Zulu are a cool inclusion (and a fixture at this point) and there really aren't any other important leaders of the Zulu nation who made big strokes in world history. But if there are, please correct me. I furthermore think his personality is rather fun and just kinda like his previous portrayals. Maybe I've just grown attached.
. Jokes aside, I really think that she is a very interesting leader just like her civ, I just think that Georgia should have a better design gameplay in future games).
