Konohamaru - he was Naruto's first fan, friend, and mini rival. He has been aspiring to become Hokage from the start and so has many years of experience. He has seen the Pein invasion, Oro takeover, and saw the war from home. He experienced personal losses as a kid (grandpa and uncle) and lived stronger because of it (as seen vs Pein).
Therefore above all, Like Naruto he is the embodiment of the Will of Fire. Kishi didn't want to give him development but reminded us of this fact vs Pein. As if Konohamaru's acceptance of the demons kid Naruto and taking him on as a rival was not enough reasons already!
Sarada would make a good 9th or 10th hokage. She needs to de-uchihafy some more and get experience. She needs to experience life as a ninja. All the previous Kage were driven for change due to their personal tragic experiences witnessed firsthand.
First lost his family bar Tobirama and grew up in war. Second the same. Third was at war. Forth had to take him students to the front line due to the reality of ninja life. Fifth lost her brother and fiance. Sixth lost his dad to suicide due to village system descrimination and every other comrade bar Gai, to war. Seventh lived through hell as a kid.
All lived without losing hope in the Will of Fire.
Sarada does not need a tragic story as the NV world is seemingly different now, but more experience of modern shinobi life would do her well. She's going to be a good hokage if she keeps working hard. Everyone loves a hard worker.