A 2014 Grand Cherokee is unibody independent suspension front and rear, right?
I'd think the 4Runner will be more obviously a truck. Not bad for a truck but is going to be obviously less highway friendly.
The GX is a luxury truck but still a body-on-frame, solid rear axle truck like the 4Runner. I'd imagine will feel OK to you (and they are very nice) but if it's handling that you're after for pavement you may still notice. What makes a GX470 better than the 4Runner is how quiet they are, how much they soak up highway bumps and vibration, not that it's any better in "spirited" driving.
KDSS isn't magic, the laws of vehicle dynamics and physics still apply.