A new Gangplank E (Because everyone complains about the current one)
Damned if you do, damned if you don't.
Since everyone hates GP's E, yet it's got fine counterplay, what else might be good for Gangplank's kit? In his lore, he's supposed to be this brutal pirate lord that out muscles, out wits and out survives his enemies.
What comes to mind for me is:
1 - Another gun, probably a blunderbuss for a cone of AOE damage that knocks enemies back, giving him wave clear and CC for surviving.
2 - Creating terrain, either a stack of crates appearing that can be destroyed by the enemies but they need to auto attack them
2b - laying a line of gunpowder down and igniting it with Q, creating an impassible wall of fire
3 - Having his ship shoot a single cannon shot at a nearby area, knocking back and dealing damage to enemies near it (Think a Xerath 'Orb of Destruction')
4 - Some sort of old school pirate magic or 'pirate's luck', having a whirl pool appear at an area to slow enemies and damage them
My favorite idea so far is a fifth one where he take a hand full of Gunpowder and throws it in the face of a single enemy or an area. This would 'blind them' like Quinn's blind and then he could either escape while they can't attack him or reposition. Q-ing them might reset your passive as well, making him great at skirmishing. Using your passive on a 'gun powdered' enemy would make nearby enemies explode sort of like a Brand passive.
6 - A telescope to see in a greater range around him like Quinn's ability, then increasing your Q range as well (Like a make shift sniper scope)
7 - More magic, this time a skill shot curse that would probably be a screeching spirit that makes all enemies hit take increased damage.
... if you just took those 2 stupid aspects away it would be fine...