In tourny play, X is #1. No question about it.
The thing with X is her safety. SC2’s system is very risk/reward oriented, and a lot comes down to simply making the right decision at the right time. You guess right, you are rewarded. You guess wrong, you get punished.
Well, it’s true that X doesn’t have very big rewards, but she rarely, if ever, punishes you for guessing wrong. This makes her PERFECT for tournament play, which is conservative anyways. Plus, her rediculous safety, poking, and easy h/m/l mixup allows her to establish momentum, and total lockdown.
Just think about it. 90% of the time, all X needs is AA, 3B, and 3A. AAB when you see a counter hit. 3B keeps them from ducking. 3A is fast and does pretty rediculous damage for something that fast. 3AK is an NCc. Plus, 3A is a great anti-step tool, considering how it hits low. Technically, it IS punishable on block, but considering how worn-out and nervous people tend to be in tournies, consistently punishing it is annoying. As an Asta player, I have trouble punishing X’s 3A 'cause my natural inclination is to use FC 3K on block, which isn’t quite fast enough to hit her consistently.
And of course, you have 22_88B. This is all she needs from mid range, and is just annoying as fuck in general.
Finally, X has matchups. She’s the one character who has a good advantage over Cervy (yes, she 0wn5 Cervy, ranking project be damned). And her bad matchups aren’t that bad. Yoshi does very well against her, but what are the odds of you actually fighting a Yoshi, and a GOOD one at that? Mitsu can punish her effectively, but he has to be careful, as kB2 can flat-out whiff her for no reason.
Nightmare is good against her, but he has some really bad matchups that could make him a liability, so they could pull counter-character on you if you won. Kilik is good against her, but again, not too many good Kilik players out there. Talim can take her, but like Yoshi, the odds of you meeting a good Talim are very low. Asta can match her, but only if he turtles like crazy.
Plus, no matter what matchup she’s in, X does not have to adapt her game AT ALL. Where as EVERYBODY else MUST adapt to her. So while most of her matchups are only 50/50 on paper, her psychological advantage is usually enough to give her an edge in just about every fight. People just plain HATE fighting X. Combine that with the fact that turtling is the ONLY effective means of fighting roachy X, and it’s easy to see why she’s #1. In an environment where you get punished for making mistakes, she’s the one character where you’re not that likely to be punished, even if you guess wrong.