As others have suggested, the main problem with EPCOT is you have a hand full of decent attractions that people flock to, and then a bunch of stuff that no one shows a whole lot of interest in.
Test Track is pretty cool. Mission Space seems to have lost much of it's luster with the current state of our space program, and the retirement of the Space Shuttles. Ellen's Energy Adventure is still relevant, but DESPERATE need of a renovation, and updating. A lot of things have changed over the years.
Innoventions needs a reboot.
Journey is a shadow of it's former glory, and is in desperate need of a refurb. Living with the land is a cool attraction, but not a tier 1 attraction. The Circle of Life . . . meh. The Seas is cool, not a HUGE draw, though that may change some with the Finding Dory movie out now.
World showcase has just two rides, and they really dumbed down the Gran Fiesta Tour with those silly video screens, so my vote is for a refurb there too. In short, half of Future World needs something done with it, and World Showcase has been stagnating for a bit too long.
Now, don't get me wrong, I LOVE EPCOT, 2nd favorite park only slightly behind the Magic Kingdom, I just feel that it has been way too long since Disney put any real effort into it, and it is starting to show.