They both have such excellent service, and equally spacious entry level rooms with great views, so you will be very happy at either hotel I think.

Ritz-Carlton has the better location for leisure travel and proximity to great restaurants, and as I said the convenience of having direct access to Tokyo Midtown would be a real advantage for a family traveling together, or anyone for that matter. It also has a swimming pool, if that is important to you.

You will certainly be fine in any room category at either hotel, but I would suggest that you consider booking a slightly higher room category if the price difference is only marginal. Sometimes being booked in even the second or third room category is enough to place you higher in the upgrade pecking order at hotels, which could land you in a top room category or even a junior suite/entry level suite if you are lucky.