I have no idea why Tomoko said such sensible thing at the end, and Yoshida nodded solemnly, but anyway it is quite revealing. Yoshida is a good friend when it matters, she and Komiyama would make a sober force if for once they could hold it together.
Tomoko likes a quick grope and an illicit peak, yet her heart likes being mothered. She's a cultured man (also notice that she lost no opportunity to take a good look). Based on this, the top contenders are this girl and Asuka. Specially when considering that, these two are the ones that push her to develop into adulthood (with the others she learnt the teen ways of friendship).