Anytime Ranma decides to be straightup nice without (much) snark count as this.
After getting hypnotised, drenched and hit in the head with a boulder, Ranma gave Kana a piggyback ride back to her dorm after their fight. Not only does he fail to begrudge her for causing so much trouble, he states that he considers her a friend since most of his 'friendships' involved fighting.
In the After School omake series. Ranma gets Satan to make a pleasant afterlife for spiders, who are denied entry into Heaven. In fact, Satan takes it a step further and creates good afterlives for everyone who is denied entry to Heaven simply on the basis of species rather than individual sin. Except vampires.
From the same Omake chapter: Tsukune being very upset that Ranma supposedly died to save Yukari, calling him his best friend and having to seriously strain himself to keep from screaming at Kouma.
Chapter 6 gives us a small but touching scene where Tsukune helps Ranma back to their rooms after his fight with Chopper Rikishi. It's not that Ranma hasn't had help back when he was in Nerima when he was injured but in contrast with his other 'friends', Tsukune doesn't taunt, admonish or try to use the situation for his own benefit. He just gives Ranma his shoulder for support and simply says that's what friends are for; and this was after Tsukune got caught in a huge explosion while fighting a golem.
An odd one, but Ranma treats Inner Moka (dubbed Evil Moka) with more respect and friendliness than the rest of the Protection Committee. Doubles as a bit of a Tear Jerker, though it's Played for Laughs, when he comments that her rabid attempt to strangle him is still better than how most of Nerima welcomed him back.