I have stayed at the RC and Suiran, but for obvious reasons not the Mitsui or Prince Kyoto yet.

The Suiran is located in a bit of a corner of Kyoto, so if you don't know Kyoto well and are mainly wanting to do the classic Kyoto sightseeing areas, the location is not great. You would need to spend a lot of time on transportation by being based at Suiran. From a pure hotel perspective, I would prefer the RC over Suiran, though getting the rooms with a private outdoor hot spring bath is a big plus for Suiran in my view. If you are a seasoned Kyoto traveller who is more looking to find a quite nice corner of the city, relax, have some great dinners, nice walks, and not too focused on seeing a lot of things, Suiran is a great choice.