We have four day 1 park per day tickets and are trying to decide how to distribute the days. I originally thought 1 park per day sounded good, but am now reconsidering Animal Kingdom. We are Disneyland regulars with young kids and this will be our first time to WDW. While my family likes animals (going to the zoo, aquarium, etc.), I wouldn’t say its what we are most interested in. It seems like Animal Kindgom has equivalent attractions in California which we have experienced many times. Tough to be a bug, Dinosaur (seems very similar to Indy), FOP (seems very similar to soarin). I do understand that Pandora is amazing, but with very few truly unique attractions (safari and Everest), and very limited entertainment because of the pandemic, would our extra day be better spent at one of the other parks that have many attractions that are completely unique to WDW? And if so, which park? We won’t be back for a very long time (if ever), so it’s an important decision for us. 
.But I would try to do one day in each park, or even expand your trip to 5 days. If you HAVE to skip one park and Remy isn't open yet I'd skip Epcot given it current state. Test Track pales in comparison to RSR. There really isn't a must do ride in Epcot right now, until Remy(and GOTG) opens. Frozen Ever After is fun but I wouldn't burn a park day on it.