Any collection with a marathon and a tuna can is a good collection in my eyes. For you as odd as this sounds I feel like you need a modern basic watch to round it out. Gs snowflake is my first thought. I also think given what you have you would appreciate a mm300.
Depends on the style you want obviously as there are a bunch of good options at that price point especially if you go used but my personal choices would be sinn or a seiko mm300