Considering your preferences and the aesthetic choices you've outlined, it sounds like going with diamond trims for your Netherite armor could create a unique and visually appealing combination. The thematic connection between the End, ocean, and Nether adds a nice touch to your overall appearance in the game. Plus, if you have a trimmed tools pack and think diamond looks better on tools, it's a cohesive choice. Ultimately, go with what you find most visually pleasing and enjoy your adventures in style!