There are just sooooo many to choose, is it a sound mod, a graphics mod (skins/textures/dress/ocean/sky...), a realism mod, a 'helpful' mod (like a 50kts boat and 50 eels

), don't make me choose!
I love the lifeboat and debris mod, if it's early years (pre-Laconia) and it's a solo vessel I love to surface and slowly work my way through telling the people which way land is! So that'd be it.
Or there's always the...