Our second least favorite park to visit by yourself is Magic Kingdom but maybe more appropriately it should be our 3rd best favorite Disney World park.
Magic Kingdom is awesome and if you do make it a solo adventure, you should. No one is going to frown upon you for riding an attraction and you can really enjoy the pace of the park all on your own.
M.K. offers a wide-variety of food and drinks that sometimes are too much for the family. For example, you are more likely to eat lunch at Cosmic Ray's Starlight Cafe or another dining restaurant rather than maybe eat at the little kiosks around the park and trying different foods.
I know when I went by myself, I enjoyed snacking more than I needed to have a sit down lunch or dinner with the family, so in this case, I had the egg rolls and the chicken and waffles later in the day. Throughout the day I hit food carts rather than restaurants and it was much more enjoyable in the end.
As for park itself, there is a lot to do and a lot of things you will likely skip because you are by yourself but that isn't a bad thing either. Some attractions are made for family and while you most certainly can ride It's a Small World by yourself, getting the song stuck in everyone's head is far more enjoyable.