Test drive both for extended periods of time, I think that should help clear things up. In my opinion, they have very different dynamics behind the wheel. "Better" is a personal preference in this area.
As far as an overall vehicle, I love the WK2 Jeep. (Current GC) It is the perfect mix of all things that I am looking for in an SUV. I understand to others it may not be, it just depends on what you value. I wanted something I could tow with, but still park in smaller spots in the city. The 4runner and GC are almost the same size, but even the V6 GC can town 6200 lbs; the 4runner is capped at 5000. I also wanted a nice interior, again this might be opinion but I feel the GC has a much nicer interior. (especially the Overland you are looking at) I think the interior of the 4runner might offer a bit more space, but that was not a huge concern for me.
Another thing to consider, the ZF designed 8 speed in the GC is a great transmission, and a nicer unit than the older 5 speed in the 4runner. It will provide quicker and less noticeable shifts than the 4runner, while returning better fuel economy. It's also used in many other vehicles:
http://en.wikipedia.org/wiki/ZF_8HP_transmission
As far as reliability, stats will show the 4runner will probably have less issues. That being said, my folks have a '14 GC and have had zero issues besides a bluetooth module that needed replacing. A friend of the family has a 2012 4runner and has had a few minor issues, so like anything else it might be luck of the draw. I recently pulled the trigger on a '15 GC myself based on my experiences with my folks '14.
Let me know if you have any specific questions, I cross shopped the 4runner with the GC a lot before I made my decision.