Taking a look at my list, only two are “nostalgia” entries that I played in full as a teen (GTA Vice City, MGS3: Snake Eater). The others are more recent playthroughs, although the games themselves range in age (San Andreas, Ratchet & Clank Tools of Destruction, AC: Origins). I took a break from gaming from about 2006-2013, and have been spending the past few years trying to catch up on what I missed and to stay kinda current, so I am hoping to add some genre and series variety to my Top 5 this summer.
To your question about nostalgia’s role in rankings, I feel like video games make nostalgia a more complicated factor than other artforms due to the interactive element. For example, Jak II was my favorite game after I played in 2006 and I had continued to claim it as my #1 up until a month ago when I finally replayed it. What used to feel so tight and fun was now frustrating, the controls simply not as advanced as I have become used to over the past few generations. Now, I wouldn’t give Jak II 5* or have it in my Top 5 games list, which actually bums me out. But nostalgia can only go so far when the artform relies on your ability to interact with it. It may be a more powerful force when it comes to 2D games due to the simpler nature of their controls, but the PSX and PS2 generations seem likely to take a bit of a hit as developers continue to improve 3D controls.