Tough question as I really like both.have also done the Maldives three times. I thought the Maldives had superior diving and snorkeling, lovely water and beaches. The Seychelles have a bit more varied terrain to the islands but also have lovely beaches and water. I can't say I like one over the other. I think it depends partly on the time of year. We went to Maldives in Jan and Feb timeframes and had very good weather. Seychelles our first trip was late August after a safari and the weather was beautiful, but extremely windy so beaches were not too practical as sand was blowing everywhere. The next two trips were in April and the weather was beautiful. I would also not go to the Seychelles at Christmas time as I heard can be quite rainy. I think with Nirth Island you need to go during certain times of the year as if it was really windy or rained a lot I don't think it would be that enjoyable.
The place we really want to try next is the Brando. I have some friends who just returned and loved it.