Xayah+Rakan seems like the strongest pick botlane now

That's part of the issue why he is mostly picked only along a Xayah and very rarely with someone else, but that still doesn't excuse the fact that Xayah is too strong right now.

I am not a Xayah main, but I love playing her, as she's cute, but I do want her nerfed, and that should say something, if even those who like playing her feel she needs nerfs (well, excluding the bronzies or others with bronzie mentality that act "she's fine, you lost to her because you're trash, not because she's too strong").

She was fun at release, made it so that both groups had to play around her feathers, but now, that interaction is kinda taken away because she does so much damage even without 3 feathers on E. Right now, her E needs slight nerfs, and maybe her shared W, but what she really needs is the adc items toned down, otherwise, it will keep being a "nerf X, Y becomes the best, nerf Y, Z becomes top tier" because in the end, it doesn't really matter who the picked ADC is as long as he can nuke faster than the enemy ADC, there is no more lane fluidity. "Hey, they have a Lucian Thresh lane, need to be careful not to get hooked" is still there, but..."Oh, I got hooked? No worries, Janna/Lulu/Rakan will shield me and the enemy just can't burst me fast enough, then I burst them".

If the support isn't resident sleeper and the Xayah has basic game knowledge or is equally good as the other ADC player in terms of skill, she wins lane.

That's my personal problem with this combo.

Xayah is strong by herself, while Rakan honestly feels weak when playing without her, since the double E range is MASSIVE, compared to his base one.

When Rakan plays solo, he loses a lot of safety, when Xayah plays solo, she loses a tiny bit of damage from her W that 90% doesn't get procced because Rakan rarely has time to AA.

I think the one with bad info here is you. Xayah doesn't start Q when paired with Rakan, but W. Trust me, I do this all the time with a friend who's a support main, and guess what? If he hits the W, the target either dies and/or blows summoners, as Rakan has ignite. Try it if you don't believe me, the W shared is too strong at early levels, that's why I said the interactions should be slightly nerfed. if you never tried it, don't say it's not applicable. The damage they got together is too high for anyone to stand at level 1. Some Rakan's go Unsealed Spellbook and take both Exhaust and Ignite at the start, thus guaranteeing a first blood or summoners blown. Again, try it before saying it's impossible, as I assure it is quite easy to do and get kills.

And Xayah was considered UP at release, have you even checked the forums back then?

Jinx has a slightly better winrate by 0.08%, Twitch has indeed a better winrate by a bit more, almost 1%, but look at playrate and ban rate as well, Xayah has 10.61% playrate and a 2.87% banrate, while Twitch has a play rate of 3.29% with a banrate of 0.45%, according to champion.gg, that's a 3.2 times more playrate, so we can safely assume that the almost 1% he has over her in winrate is because of the massive pickrate she has over her.