I would just caution you that this is a tricky comparison to make, and it depends greatly on what type of off-road driving you expect to do. If you are going to drive on some rough dirt roads or mud, any of those vehicles will do, but in a pinch I will take the Rubicon hands down.
I realize that the Rivian is getting good reviews in magazines, and it's easy to get caught up in new technology and specifications, but the biggest issues that I encounter when rock-crawling on steep, narrow, exposed trails, with people trying to pass me in the opposite direction, require a narrow vehicle with large approach and departure angles, and preferably an actual locking differential. Big tires, skid plates/rails, and overall strength/sturdiness are also critical. Clearance and breakover angle can be important, but people tend to put too much emphasis on them in my experience, since you can often compensate by choosing the right route. Manufacturers are constantly saying that their new technologies are just as good or compensate for these features, but they have been saying that for years, and it hasn't been true yet. The Rivian looks good, and probably better than what I drive, but it doesn't compare to the Wrangler for my money. My friend has a Rubicon, and I'm amazed at what he can do.
When you are trying to drive over huge boulders while looking over a sheer 500-foot drop, a gigantic RAM pickup is coming up the trail towards you, the adrenaline is pumping full blast through your body, and your jaw aches from gritting your teeth for the last hour, it will become a lot less theoretical and you will understand what I'm saying.
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