I guess for me it's exactly the opposite. I was only halfway interested in him pre-chip, and most of that interest was due to Becoming and Spike's decision to make a truce with Buffy. If he'd never done that, he'd have never caught my interest. Sure he'd have been funny, but I wouldn't have fallen for the character.

I started liking him in s4, due to his weaknesses as shown in s4 and I fell in love with him in s5 when we saw the good he was capable of when he falls in love.