Have to go with Magic Kingdom and EPCOT.
Right now, Hollywood Studios is a skeleton of itself. There's a lot of construction and a ton of closures. Once you finish Tower of Terror, RnR and Toy Story Midway Mania, there's not a ton left to do. It's has the weakest restaurants (opinion) and is not really worth the day (right now.)
Animal Kingdom is great - the theming is fantastic and of all the parks, it's probably done the best job of maintaining its roots (no pun intended.) But it's kind of a half-day park. Unless you're an animal lover, there's not a ton to do after going on the safari and Expedition Everest.
Magic Kingdom is fantastic. It's vintage, classic Disney. If you want to experience Disney, you go to Magic Kingdom. The restaurants aren't the greatest, but if you could secure a reservation at BOG, that definitely helps.
EPCOT is great for food. It lacks the rides the other parks have, but it's a really good time. My family loves to eat our way around the countries.
DHS lacks the rides for your kids. It's a thrill-ride park, really. Your 8-year old may enjoy ToT, but your younger ones won't be able to go on. At least EPCOT is a great spot for your kids to learn about culture and a chance for Mom and Dad to enjoy some great food and a drink or two.
I recommend EPCOT and Magic Kingdom. MK has a couple roller coasters if your 8yo is into thrill rides and enough family rides for your entire group to enjoy.