For 2D I, personally, would install MonoGame then add Box2D library and make my own thingy with blackjack & h***kers.
But that because I like to code. If you want to ship as fast as possible then that would be a terrible idea for you.
Unity has more 2D tools than Unreal, which helps finish development faster.
I’d say in case of a “real 2D” game you would use not even 1/3 of Unreal’s features anyway so why have them packaged into your binaries if you ain’t using any of them?!
In my opinion both Unity and Unreal are too much for a 2D game.