Willow's relationship with Tara, which was both groundbreaking and heartbreaking, gets the brunt of the attention. It's often regarded as the best romance the series had to offer, and that's fair. Still, because of all the buzz that Tara and Willow get, it can be easy to underrate her time with Oz, the quiet werewolf that shows up in season 2 and leaves Willow in tears during season 4.
Still, Oz is perhaps best remembered for his dry wit. This is the character that very frankly asks his aunt if his cousin's a werewolf, and is perfectly accepting of all the strangeness that infects his home town. He's just along for the ride, and he's happy to be there. No other character was a better vehicle for comedy over the course of the show's run (with the possible exception of Anya), simply because Oz was so wonderfully dry that almost everything he said was hilarious.