Responses to questions like this can be misleading because they will usually have personal preference built into the answer. Both parks, unfortunately, have been pulled down by closures and vacant buildings. That said, there is plenty to do at both, depending on what your family likes.
For example, if you've never been to HS, the shows alone take up an enormous amount of time. My family never gets tired of the shows and will do them all on every trip. Plus, HS has always boasted a large number of characters, which can be huge time hogs. When my children were little, and wanted to see every character, between the shows, the rides, and the characters, it could take us 2.5 days at HS to get everything done.
Epcot is really two separate parks, and it is silly to think of it otherwise. If possible, try and experience Future World one day and WS on another. We usually utilize hoppers to jump over to or away from Epcot multiple times during a trip. For us, experiencing Epcot in total, but in multiple small doses, works best. That said, to effectively tour it in total would take 2.5-3.0 days (again hitting all rides, characters, shows, shops, multiple restaurants, etc.).
Bottom line is that both parks still have plenty to do, if your travelling party wants to experience everything the park has to offer. For those on short, 3-5 day trips, once MK and AK are factored in, neither park can be toured in it's entirity. That's when personal preference needs to come into play, and that's why answers like 'it's a half day park' end up in a post.