Savage Tide (Dungeon Magazine). I consider it Pathfinder given the writers and nature (a 6-part mega adventure with different writers for each book). My first 5E conversion attempt. Made it halfway with some modified content, and found the village defense satisfying enough of an ending that I didn't convert more. I did something very similar to what
@TheSword recommended for treasure and critters.
Kingmaker. Ran it probably 25% original material and 75% modifications. The framework is great, the mini game of kingdom management (after you get bigger) is not. The adventures falter a bit without help, such as Dudemeister's modifications from the paizo forums (so influential the computer game used them). Ran it to completion. Amazing as the adventure is so open that there's really no way to tell how your party is going to go. Infinite possibilities for NPCs and relationships.
Skulls & Shackles (next campaign). Prepping it right now. A lot of work, a lot of work to be done, mostly with the storyline and not converting systems.
Summary: I can work with converting most anything. I'm currently using Fantasy Age (Dragon Age) rules from a 3d6 system and easily subbing in OSR and 3E adventures. I just need a good story and framework. The rest is just having a monster manual, difficulty check table, and an idea of treasure.