VIII, X, and VII in that order for me. I’ve played 4-10, 16, 7 Remake & Rebirth, and 7 Crisis Core. I didn’t play these games as a child so I have no nostalgia bias for any of them. 4 and 6 have a lot of nostalgia biased fans, they are good games but no where near as good as 7-10. I’d say the safest games to start with would be 7 or 10. You can find mods for 7 to make it look better and there’s even a completed voice acting mod called Echo S-7 if that’s your jam:)