OG Starcraft I got a soft spot for because everything in the menus was animated and provided you with statistics and other cool looking shit when you hovered over them with the mouse.
Despite the game being absolute ass, Reach's UI was great. It was easy to navigate, had cool art depending on which lobby you were in or what campaign mission you were on, and the Active Roster was also a nice addition.
NFS: Underground 2 is also one of my favorites. No matter what menu you were in, your car would always be there and you can always spin the camera around and rotate the car. The area where the car is along with the city lights in the background really made it feel like you were there. Also during the singleplayer, every shop had a different background so finding all of the shops hidden in the world just to see what kind of background there would be was cool.
Persona 5's is so god damn stylish and awesome to look at. Everything is different too. I gotta play this game more.