I have the minimig and the xbox1 with the last winuaex.
If I had to choose one to run Amiga games only, I would choose the minimig.
The screen quality is better on the minimig (even if my xbox is connected throught RGB in 720P). The minimig is small and consumer 2watts. The minimig rendering is better IMO even if the crop version of winuaex is cool to play overscan.
There are 50 cool AGA games in which 15 are probably really using the AGA chipset.
Ex: Chuckrock 2 AGA which is a cool plateform game got the same visual on ECS/AGA.
I got a lot of examples like this