To the original poster, I don't know if you have sailed with NCL but I would argue that MSC is more akin to the Norwegian ships rather than the Oasis class. If are are familiar with NCL they have an enclave called the Haven, on the MSC ships its the yatch club.
We have sailed with all three cruise lines, along with many others. Now we don't mind the MSC ships but of late, have found ourselves sailing more with Celebrity, Princess and Cunard. For us, we like the Solarium on the Oasis Class. We also like the fact that we have the "run of the ship". With the newer Princess ships they have the Sanctuary rather than the Solarium. However, you can chose whether or not you want to pay a bit extra to patronise that area. On MSC, there is no option, especially on the newer ships. You have to pay a lot more to sail in the yatch to enjoy areas at the front/bow the ship that in most part are free to use on other lines.