I personally feel that attachments should act more like side-grades rather than straight upgrades like how different weapons work in TF2. Objectively, the best version of a weapon should be its base form and attachments only serve to specialize it in some niche. Right now items such as angled grips, laser sights, red dot sights, mag-harnesses, etc. feel like they just make a weapon better, not different in terms of gameplay.