If we are just talking strictly anime then it's the scene where she manages to say goodbye to a teacher and then she goes to the convenience store and sort of mumbles to an attractive guy who works there. The fact she's so happy about it is funny and I like the art where she's dashing through the streets happy.
[spoiler](/m "In the manga there are a few scenes I like off the top of my head many of which come from the class trip which was such a big turning point in the manga imo. But outside the school trip was the scene earlier on after she'd met Komiyama where Tomoko walks into the bathroom and finds Komiyama eating in there like she does and kind of realises how similar they are their whole relationship has some good scenes like the one after Komiyama finds out Tomoko is meeting Yuu-Chan and they both meet up again. The next day at school they both awkwardly try to make conversation and remember how it was back in Middle School when they tried to be friends for the sake of Yuu-Chan. Their efforts to put aside their differences are funny mostly because of how similar they are if they looked past all their petty arguments and jealously issues over having this one friend they'd probably get along well.
On the school trip again this sort of comes into play when Tomoko goes to the bathroom and is staring out the window and playing with her phone out of boredom Komiyama walks past and was going to ignore her but finds she can't and they talk awkwardly but mostly friendly. I think partly they took Yuu-Chan asking them to be friends to heart but I always feel like they kind of want to be friends and now and again Komiyama especially reaches out a bit and not just because she wants to get in with Tomoki.
I guess I can't go through the school trip without a Yoshida scene I just completely fell in love with her during that whole thing she's so expressive even when she's not beating Tomoko up. The whole scene where Yoshida is enjoying the view and Tomoko asks if she likes high places because she's a delinquent is one of my favourites not just because of the angry reaction but the meaning of it apparently there is a saying about stupid people liking high places so she basically said Yoshida is stupid and there is a couple of great panels after of Yoshida looking quite hurt I think about that time I fell for her. The scene when Ucchi is trying to wake Yoshida and Yoshida is imagining Tomoko trying to pinch her nipples again is maybe the scene I laughed out loud the most at it's just the way they drew Tomoko in that scene it cracks me up. And finally the whole steep climb where Tomoko after goading them up and Yoshida taking the bait since she's not too bright either. Tomoko hurts her ankle and Yoshida carries her to the top I feel like Yoshida while a bit dim and prone to anger is generally a nice person and she did it because Tomoko apparently really wanted to go to the top so much that she was willing to goad them into it so carried her. Of course when they do get up there they find out the reason she wanted to do it is so she could make them praise her for it and they walk off which is a hilarious scene.
Oh and just thought more recently the scene where Yoshida is talking about the strange UFO building that nobody wanted to clue her in on before with her Yankii friends and they reveal it's a love hotel just that face of realisation and her dreams being shattered is funny. I could talk about the arcade and the umbrella too (Tomoko really does seem to have misunderstandings when it comes to people being nice when she always forgets her umbrella) Tomoko and Yoshida just seem to have this weird relationship much like with Komiyama you get the feeling they are friends even if they don't really act like it or seem like they want to be. They have this domme/sub relationship lol")