I've extensively worked in both engines, and taught people how to use both engines.
Unity is such a flimsy piece of stuff, and the bane of my in-and-out work life. I've seen Adobe products that crash and load less. People claim that just because it makes use of C# that it's easier to get into, and yet they commonly forget that it's so absent of any decent features out-of-the-box that you had better be a bloody expert at either math or Google-fu to get your work done. Unity's own basic templates that give you (such as character controllers and materials) are, to put it bluntly, stuff. The entire system regarding platforms is handicapped (it takes about 2 hours for my work project with a lot of art assets to switch between platforms), and JESUS HELP YOU if you plan on using version control with any Unity-specific content files (like scenes, prefabs or meta files).
Is it fast? Sure. But it's not reliable, it's core configuration is not flexible (there's a reason most Unity games have such an extremely limited amount of options to configure, and it's not developer laziness surprisingly) and it's loving ugly. Add on the abysmal licensing scheme by comparion to Epic's offering, and you've got yourself a giant series of headaches.
Unreal comes with a whole slab of functional templates and base content items. It's got tutorials both in and out of engine (and the documentation isn't notorious for sucking, unlike Unity). If you want to do something in Unreal, there's probably already a system implemented in the engine for you to use without having to wait 10 years for the feature to come online (looking at Unity's inability to play movies until the end of the 5.X.X line), and they're never half-arsed (don't use Unity's AI system, for the love of John Carmack). Blueprints means anybody can jump in and implement, and you only have to touch the C++ stuff if you absolutely are more comfortable with it (there's very,
very few things that aren't exposed to Blueprints, and thanks to recently upgrades Blueprints now bake into C++ for the speedup). And even if you won' bother to give your users the necessary customisation options for their PC experience, Unreal Engine games all have config files so the user can manually setup things for their own benefit.
Unreal is fun, it's more feature-packed and it doesn't give me a loving aneurysm at the end of every work day.
Use Unity if you need to rapidly prototype extremely quickly, or you're a minor hobbyist. If you actually want a career in game-dev, Unreal 4 is a lot closer to the engines that most game developers use.
A stuffty craftsman blames his tools.
That's assuming the tools aren't broken.
all four of these games are built on unity.
Doesn't mean good can't come from it, just this year, we got games like Cuphead, Snipperclips, and Yooka-Laylee that were made on Unity
Am I supposed to be impressed?
The design is good, sure. Doesn't mean I agree with the execution or technical aspect of any of those titles.