I've recently had the experience of taking several road trips in rental vehicles and thought it was time I share my feelings with the world. I have not looked at the specs for either; I don't know the horsepower or cubic feet of storage. This is based on feel over stats.
The Jeep was used for a 12 hour NC to NY drive, while the Toyota made the shorter 9 hour voyage to NJ - both trips gave me plenty of wheel time to evaluate the SUV's. I suppose I should add a disclaimer acknowledging that these were rentals, and perhaps mistreated. Onward!
Engine - Slight edge to the Jeep. The 4Runner seemed to work a lot harder getting up to freeway speed. The Jeep was also had a bit more grunt leaving the stoplights.
Handling - Jeep wins decisively. The Grand Cherokee showed far less lean and provided far greater road feel through the steering. I felt much more in control, hence, safer. The Toyota felt far more top heavy than the Jeep, and steering was pretty uncommunicative. Both drove like trucks, but one (Jeep) felt far safer.
Style - This is purely subjective, but I'd take the Jeep any day of the week. The slanted rear window may have cut into carrying capacity but the outward lines were very pleasing. The 4Runner was a little boxier, a lot more bland.
Interior Comfort - Hard to pick a winner in this category. Both had decently supportive seats and a nice driving position. The 4Runner did, however, have annoying orange gauges.
Cargo - This might be an unfair comparison as I seriously loaded up the 4Runner. It did seem to have more room, probably due to the vertical rear gate rather than Jeep's previously mentioned slanted window, but I had to remove the third row seat to take advantage of it. Because I'm an overgrown 9 year old, I jumped in the third row seat to see how it felt. I would feel terrible strapping a stuffed animal into these things, let alone a child. This is not a seat. They were also a pain in the ass to put back in. Granted, it was my first time attempting to do so. So, 4Runner bigger, but took more work to exploit the size.
Other - I give the Toyota big points for the powered window in the tailgate. I subtract even more points for having an archaic footbrake rather than a handbrake. Might seem trivial to you, but I hate those fucking things. The Jeep offered a direct input for the iPod, which obviously scored well with me. The 4Runner did not, but played mp3 cd's, which meant I had to specifically burn a few mp3 discs for the trip. Not a big deal, but plugging in the iPod is so much easier.
Verdict - I'm obviously picking the Jeep. Not even a close comparison. I was expecting the Japanese half of this comparison to do so much better...yet I was wrong. Toyota is becoming rather bland. GM kind of bland. And I should give credit to the team at Jeep - this is a truck I would definitely consider buying.
Keep an eye out for my luxury rental showdown: Cadillac vs Lincoln.