Your preference for shirt fabric is for traditional, solid colours (white, blue, light purple, pink). You are not against flair at all, but since you almost always have a jacket on, you prefer shirts that are easier to match with other fabrics. Hence the solid shirts are then very flexible. You can always add interest or flair with a pocket square, boutonnière or cuff links. That being said, you've rightly identified fit as the key factor in any shirt, and that will always be far more important than pattern or fabric.
All shirts 100% Cotton.