Hi, Michelle! Both Tutto Italia and Via Napoli offer some delicious Italian food options, and they are both very popular with theme park guests. I think it depends on what type of meal you are looking for.
Although the restaurant is theme park casual, so shorts, t-shirts, and loud kids are welcome, there is a more upscale feeling about Tutto Italia. You will also find a more extensive menu when it comes to things like meat, pasta, and seafood.
Via Napoli has a definitely more casual vibe, and absolutely incredible food, but the strengths here are on things like their pizza. We just enjoyed an incredible pizza margherita there a few weeks ago, and it rivaled the authentic pizza we had when we visited Napoli a couple of summers ago. We also thoroughly enjoyed our appetizers. Other entrees beside pizza that you will find here are basic pasta dishes and parmagiana style entrees.
We love both restaurants, so either option would be wonderful. Try and decide which your family would prefer.
Other restaurants at EPCOT that my family really enjoys include Restaurant Marrakesh and Teppan Edo. I think the food is wonderful, and I love that the menu is different yet familiar enough that my kids will try new things!
Have a great visit!