Running the game you're asked, not the game you want

Dungeons & Dragons 5th edition is not a perfect system. It's heroic fantasy, which often doesn't correspond with my love of dark and gritty fantasy. In fact, I have a bookshelf full of more dark, grim, perilous RPGs I would love to run. This campaign actually started out in B/X D&D, but we grew to like our characters so quickly that it was agreed we didn't want them to die casually. It was a good lesson in why D&D has drifted the direction it has: people want to invest in a character, and see their story out. Frankly, I think that's not unfair.
This leads to an interesting conundrum I'm sure multiple GMs have faced. There are many games I want to run, but if I want to run games for my friends, I need to run games they want to actually play. My best friend has specific tastes. He's not fond of character death (he prefers little to none), and wants to see a story evolve for this characters over the course of a campaign. Another group I run games for do…