You know that Royal has solo cabins, too? I've stayed in one on Harmony and had one booked on Quantum. What NCL excels at for solos is the Studio Lounge communal space for those in solo cabins and the hosted nightly solo happy hour for all solos, though I'm not sure that has survived the re-start.
To the OP, I think Royal would be a fine fit for you. As to the floating amusement park comment, there is simply nothing like Oasis class. I enjoy the variety of musical entertainment all over the ship. It's wonderful to sit at the Trellis Bar Central Park and listen to a string trio or classical guitarist in the middle of a beautiful garden. That just doesn't exist anywhere else at sea. And the variety of dining experiences really is wonderful from a hot dog shop to molecular gastronomy! I get excited about dining on the big ships.