I started a new save file for the sims bustin out on gamecube. This is probably my 30th+ time playing this game and that isn't an exaggeration. It's one of my comfort games.
Anything on the n64. Especially mario party 2 and beetle adventure racing.
I still own and play most of my childhood games so the only ones that really make me feel nostalgic are ones I remember playing with friends growing up.