>>12014571 (OP)
>X1
Great, but too easy.
>X2
To me it's better than X1 except for the aesthetics and soundtrack.
>X3
Somehow not as fun as the previous 2 and has a bunch of gimmicky features like the ride armors or Zero, still good and worth playing.
>X4
People overrate it. Cool anime cutscenes but has some of the most boring level design in the series. You can play as Zero and he's cool. Ok game but not as good as the first 3.
>X5
Best lore if you're autistic enough to care about it. I find it slightly better than X4 at some points, worse at others, and Alia annoying you all the time with tutorials sucks. Also has a weird RNG mechanic that can screw up your progression. No reason not to play it if you enjoyed X4.
>X6
Actually challenging game and I like it more than X4 and X5 just because of it, but it's kinda jank. The mechanic where a level randomly goes dark is extremely annoying. Apparently there's an impossible jump in one of the later levels depending on your setup but only people with bad taste wouldn't always have mobility chips equipped anyway so I only learned about it years later on youtube.
>X7
Was my first PS2 game and even that bit of nostalgia can't save it. Might be worth a playthrough to laugh at it.
>X8
The most gimmicky stages in the whole series, absolute garbage platforming for most of it. Just as bad as X7 but just by being 2D and having a better plot people tried to gaslight themselves into thinking it was some sort of return to form.
tl;dr: play at least X1, X2 and X3