Platforms I own: PS2, Xbox 360, Wii, PS4, Xbox One, Switch, 3DS, GBA SP

The title says it all.

Breath of the Wild
Horizon
Scalebo-
Witcher 3

Horizon Zero Dawn
No Man's Sky
The Witcher 3
Farcry Primal

Since some of the best have already been mentioned...

Just Cause 2
Fallout 3 & New Vegas
Assassin's Creed 4
Metal Gear Solid V

Xenoblade Chronicles and Xenoblade Chronicles X
Skyrim
Oblivion
Witcher 3
Fallout 3
Fallout New Vegas
Fallout 4
Horizon Zero Dawn
Farcry 3 and 4

There's a lot to play and a lot of different feels out there. 

Dude, too soon man.  Too soon :(

Horizon Zero Dawn
Dragon Age Inquisition
The Witcher III
Mass effect Adromeda (since it comes out in two weeks)

Horizon And Zelda just came so you should get those, Xenoblade Chronicles for the wii is another great option.

Yeah, try that Zelda game if you haven't heard of it.

On the 3DS maybe Fantasy Life, Monster Hunter or Pokemon.

GBA?!? Maybe GTA or Pokemon, can't be many on that format I would of thought.

Breath of the Wild is probably the only one you should be playing right now, it's the next big step in open world gaming. GTA3 being the last.