Hahahahahahahahaha what a comment! Lately I feel that japanese authors have been invested on putting on a twist to things instead of letting best girl win. Soooo, that being said, I feel that this manga will turn out sad no matter who he chooses in the end.
She already got passively rejected by him at the pool when she saw the braclet and she stormed off with the "I won't lose to anyone" vibe. Now she is doing this so she can leave with no regrets.
With the Koni/Manbagi comment- I would love for the author to have Tadano think Komi is out of his league so settle for Manbagi, but my guess will be that if Tadano confesses Manbagi spills the beans that they both like him giving him the opportunity to get Komi. Hell, the manga is named after her for pete's sake! She gonna win.
The "other" girls in harem manga are always better because the MC and FMC always HAS TO BE unsure of their feelings. If not, the manga would end by the first volume. Plus first girl always has to be the winner no matter what kind of person they are (usually plain/boring/etc), So the other girls are typically better because of their quirks (genki, gamer, tsun, childhoood friend, clumsy, etc) which make them more likable/relatable to guys. That just brings the hurt when the obvious choice wins.
Only recently have some authors made it a mission to allow the genki/first-girl-after-all to win, like in Quints. Or with with We never Learn, with he genki/childhood friend -the outpour of hate was so strong that author had to make a route for everyone.