Super Smash Bro Brawl for me. It was the last smash that actually felt impressive for it's time. Don't get me wrong Ultimate is great too.
GTA IV is a great game but I don't think it's 98 meta great.
Fallout 3 I never really got far in.
I miss Littlebigplanet it was one of Sony's more creative games. they abandoned it. Like a lot of their other series.
I still need to try the Metal Gear Solid games...