Start with what the first trip must handle
Tokyo and Kyoto compete for the same limited days. Tokyo carries arrival, food, neighborhoods and modern contrast. Kyoto carries temples, gardens and cultural depth.
Give Tokyo more nights
Choose more Tokyo nights if you arrive there, land late, want food, shopping, day trips or a softer first phase.
Give Kyoto more nights
Choose more Kyoto nights if temples, gardens, seasonality and slower mornings are the main reason for the trip.
A simple model
For ten days, four Tokyo nights and three Kyoto nights often work. For fourteen days, five Tokyo and four Kyoto can be comfortable.
Count mornings
The best split is about usable mornings, not just hotel nights.