Primarily azumatt's first person mode mod, but I use that with better archery since it properly rigs the character model's arm when aiming with the bow in first person (otherwise your arm stays static and blocks your vision when aiming downward). It's a small client side tweak that adds a great deal of immersion to the world. Building in first person is also quite handy. You can scroll in and out of first person just like in skyrim, 3D fallout games, etc.

Our server has about 53 mods total for various bits and pieces (the number grew after we deprecated Valheim+) but I absolutely cannot play the game without first person mode any more.

If you're interested in what else we use, I can share our mod manifest later on.