Yeah in the end no matter how the author ends his manga, no one can satisfy anyone. There will be at least half of people whine that he's not dead, but if he's dead, the other will flame the author for killing his characters. Everyone will always bitch about something, huh?
But for me personally, I'm glad Tanjiro survived. It would be cool if there's a continuation of this main story, where will The Demon Slayers and Kakushi go in the future? Will they make some institution to make a perfect cure for Demons? What if they make a big lab solely focused on making perfect solution for immortality using Nezuko and Tanjiro's blood? What if they research the Lily that makes Muzan immortal? Soo many possibilities!!