Functionality is a nebulous term. It really depends on the functions you need.
If you're a soccer mom driving the kids around town, the Patriot stands above the crowd -- you may not get the best in any category, but oh so close to best in almost every category: fuel economy, interior space, cargo space, ride comfort, adequate power, excellent traction in snow, and can handle the occasional scrappy trail. I'm not a soccer mom, but I want all those things, so the Patriot fits me to a T.
If you have to be first away from a light, get the GC with the 5.7. Ditto if you want a luxury boat (or plan on pulling one).
If you're doing a lot of severe off-roading, get a Wrangler -- also helps you pull your friends out of the mud. Now they owe you a 6-pack.
I'm not really familiar with the Liberty, nor have I figured out why they make it . . . people must buy them.