I'll step up, as the owner of a '94 YJ and an '08 JK Unlimited Rubi.
The two doors are great for tighter trails, but I haven't had any issues in my Unlimited. The extra room the unlimited provides is incredible. On a recent trip to MA to the GF's grandmother's place, we were able to bring home a cedar chest, boockase, end table, several large boxes of various items, as well as the luggage we took with us on the trip. The longer wheelbase gets you a smooth ride both on and off-road. If you plan on carrying any more than two passengers, the Unlimited is the way to go, much easier entry and exit.
Go with a 4-door... you won't be disappointed.
ETA: I've had no issues with durability, breakage, or parts wear. I've had mine a bit over a year and am approaching 30k miles. From trails, to the beaches of OBX, to three and a half foot deep rivers in teh VA mountains, to snow... I love my 4-door.