Hi Ronald!
Thank you for submitting your question to the Disney Parks Moms Panel! As a mom of three, I would definitely recommend Magic Kingdom for your 4 and 5 year olds! Magic Kingdom is the most popular park for the little ones as there are more attractions available for them. Here are some of the attractions my little one loves: "Peter Pan's Flight", "Buzz Lightyear's Space Ranger Spin", the "Magic Carpets of Aladdin", "It’s a Small World”, and "Dumbo the Flying Elephant". You can also find plenty of
character meet and greets thoughout this park! There is no better feeling than to see your kids light up with excitement when they see their favorite characters! Ultimately, I gotta say that the best thing is the
Wishes Nighttime Spectacular Fireworks! The music, the fireworks and the flying Tinker Bell are out of this world!
If you visit the other parks, I would recommend "The Seas with Nemo and Friends" at Epcot and "The Boneyard" play area at Disney's Animal Kingdom; “Disney Junior – Live on Stage!” and "Toy Story Midway Mania" at Disney's Hollywood Studios! Your kids would love these!
Have a great trip!
Yael