The Toyota is higher quality and will likely last longer. Today's Subarus are OK these days with their major problems behind them, and Subaru has pretty much the best AWD system.

You're talking about different types of vehicles. The 4Runner is really more of a truck, where the Outback is a lifted station wagon, based on a sedan. Lookup up specs, the 4Runner TRD has a V6 with a conventional 5-speed automatic transmission. The Outback Wilderness has a boxer 4 (turbo optional) and a CVT. The former uses a lot more gas, the latter will require more maintenance and is not going to last as long. Being a heavier-duty vehicle the 4Runner would be expected to hold up better that the Outback under severe usage conditions.

Another factor might be that Toyota dealers have the reputation of being more entrenched and not backing down from demanding thousands of dollars for useless add-ons and "market adjustments" than Subaru dealers.

Here are feature comparisons. (These don't go into the issue of longevity.)

https://www.autoblog.com/buy/2023-Subaru-Outback-Wilderness__4dr_All_Wheel_Drive/specs/

https://www.autoblog.com/buy/2023-Toyota-4Runner-TRD_Pro__4dr_4x4/specs/

The 4Runner is more of an SUV. It’s probably one of the few really SUV’s out there. The Outback is a station wagon crossover “SUV”. 

I think both are great, depending on what you need and how you like the ride.

The 4Runner is built on ancient technology. This generation has been around for a decade+, with minor revisions. But that’s not necessarily a bad thing. In Toyota land, and isn’t technology usually means time tested and rugged technology. 

The Outback is built on newer technology, specifically the transmission, which is a CVT.

Besides the form factor, the biggest difference between the two is the type of engine. Toyota uses a V6. Subaru uses a boxer Engine, sometimes called a flat engine.

Subaru has a lower center of gravity due to using a fly engine. Which comes in handy when cornering, curves, or just staying stable when on trails and stuff. On paper the car is less likely to tip over.  

4Runner is one of those time tested nameplates. It is built strong. And despite not having been renewed for over 10 years, it is still a popular vehicle. 

It really depends on what you are looking to do with the car. Both are great choices depending on your needs. Toyota has a slight edge in reliability, but not big enough to discount Subaru, depending on your needs.