What actually makes a good coffee lover gift for your dad?
Start by eliminating mismatches: another mug unless the mug itself is unusually well chosen. Then narrow the list around better beans, brewing accessories, accurate tools, storage and small upgrades that improve a routine they already enjoy. Because this is for your dad, keep the activities he chooses when nobody is assigning him a task in mind and avoid dad-joke merchandise unless that is genuinely his sense of humor. A small but precisely matched upgrade can be more memorable than a larger generic present.
The strongest gift ideas usually come from the person’s real habits: what they already use, what they talk about and what would make an existing interest better.