Gen 6 Pokemon Emerald. Didn't play a lot of GBA games.
Gen 7 God of War: Ghost of Sparta. It boggle the mind what magic Ready At Dawn did with this game. Blows the crap out of most PS2 games with its amazing textures and lighting, astounding sense of scale far ahead of any portable game to date, amazing special effects and beautiful animations all while running at 35 to 40fps.
Gen 8 Killzone: Mercenary. It looks like Killzone 2. The stunning character models and environments with the post processing make it look that good.
Gen 9 Doom. It looks like Doom on console. It plays like Doom on console. It gets a lot of the effects right and not looking them side and not caring about the framerate it is Doom on console but on a portable.