For most travelers, spring and autumn are the easiest windows to recommend because they give you the broadest room to combine city walking, inland driving, tea-country days, and longer time outside.
Summer can still work, especially for coastal pacing, but it usually needs more heat management and more careful expectations around comfort. Winter is often underrated for city-and-heritage routes if the trip is not built around mountain weather.
The best season is never just a weather decision. It depends on whether the trip is more about tea, roots, city comfort, photography, or simply building a first visit that feels low-friction.