There is zero reason to lift more than 2" anyway. It is all for looks at that point.

The new Tundra is very interesting and there seems to be a ton to like about it.

In Europe, a Tundra could be insane in urban driving, depending on the country.

The 4Runner is very comfortable on long drives but not perfect. When fully loaded, it struggles in mountainous terrain like Montana interstates which means high revs and low mpg and, most importantly, the struggle is just annoying. On the other hand, with a good suspension as the TRD both would drive very well on mountain highways as in CO. The enormous Tundra cabin would be a plus on ultra long drives like Alaska while the 4R would always be better with a dog.

Now, offroad, things are less subjective and this is what I normally think about . The 4R is as big as it is comfortable in the SW. I would not have issues with a Tundra on any San Juan trail other than Black Bear (and even that is surely doable with enough care) but without a doubt a 4R is more pleasant. Still, consider that the 4R is not the best for stability offroad so a Tundra will always be better in any offcamber situation just thanks to the very long wheelbase.

The real offroad issues would be here in AZ desert trails, Utah canyon trails, and any narrow mountain trails in CO/MT/CA. The 4R is just wide enough and even so mine is pinstripped like there is no tomorrow. And often we talk rocks rather than plants.

On the Tundra side of things, it comes with more travel, I am sure, which makes it potentially much better to adapt for higher speed, open desert stuff like parts of California and Nevada and some in AZ/UT. Either way the stock suspension, TRD would not be stiff enough for this requiring aftermarket or at least aftermarket heavier duty springs.

Finally, I suppose the Tundra will have lots of features. I like the 4R because it is very basic and I use it as an all-purpose mobile. But it does feel like it is a 2010 vehicle.

For me, if I had to choose today, the only easy part would be my garage size and so 4Runner again. Otherwise, I would have to give it a very careful thought. The Tundra would eliminate some trails and require special paint protection but it would also be better for higher speed offroad driving, very long road trips, and safer IMO in offcamber offroad situations.