My favorite modpack is definitely the old Tekkit for Minecraft 1.5. I’ve probably spent more hours in Tekkit than any other Minecraft version or modpack.

As for a mod, I wouldn’t say this is my favorite mod, but I want to recommend Chalk. It’s a very simple mod that adds a chalk item, which you can use to draw arrows on the ground. It’s very useful for marking your path when exploring open areas and cave systems.