Lexus and Toyota are the same company, so you can't go wrong with any of those SUVs. The Lexus will likely be a little more expensive to maintain and fix since parts will cost a little more. But, all of those are excellent choices. The 4Runner and Lexus GX are more rugged, off-road capable SUVs. The Highlander is more of an on-road family type SUV, so I would decide among those based off what you will be using the car for. 

They are both good companies.  The 4runner is great for off-road if you are in to that.  The highlander can do some limited off-roading and is a great family SUV.  The Lexus is your luxury option and is great in many ways too, including a smooth ride.

They are all great vehicles. The Highlander is a comfortable family vehicle that is very reliable. The 4runner is bulletproof but less luxurious than the Lexus. Just keep in mind the V8 Lexus would cost more to maintain and repair as it ages, but should not have many problems. Depends on what you want but you can't go wrong with any of them. Of course there are specific years you should avoid and do some research on that using carcomplaints.com. Hope this helps!

Thanks for the tips 😀