Besides himawari and sakurako they (Ayano x Kyouko) are the most canon and obvious ship.
It's fine to have headcanons, but attempting to call any Yuru Yuri main series ship even close to canon is stretching it a bit. Extreme (understatement of the year) subtext and one-sided crushes don't equate to canon relationships in any series. Until there's actual confessions and confirmation of reciprocation, it's all Namori's tease-fest. What's "canon and obvious" to you could simply be a one-sided crush with no clear evidence of reciprocation to someone else. Even Himawari and Sakurako refuse to acknowledge their feelings for each other, so there's no romantic relationship there...yet.
I guess what I'm really saying is, Namori-sama, it's been 12 years. Maybe it's about that time.