Another argument I hear often is that Angel is lame/boring and therefore why would anyone choose him for Buffy. First of all, I personally don't find Angel boring, ever at all not even once. Even in the early BTVS seasons when we get short exposition Angel, I was interested, wanted to know more about him, wanted to know his story, who he was, how did he know about Buffy, why did he have so many wife beaters, why he wore velvet blazers, could I see him shirtless....
And as we continued to develop Angel, I find him deep and interesting, complex, trying to find his place in the world and specifically in Buffy's world, and later on in his show constantly confronting and questioning morality. Making the decisions to fight and continue to fight even if it meant never reaching your goal, your redemption. Struggling with the idea of redemption. I guess if you find him boring you found his show boring?
I agree that Spike is the more charismatic character. I happen to love Spike in Seasons 1-4, especially Season 4 where he is a freaking hoot. Of course he has to be more charismatic because he is not our central protagonist and unlike when Angel was first introduced he was also not the love interest so you are coming at it from a different story perspective. But in fact to me the Spike character in Season 4 really cut into seeing him in a serious light later on in the show. Spike is the quintessential side kick. He is goofy and funny and has quippy Cordy-esque lines. He is Joss' way of injecting his witty dialogue that we all love. That makes me love Spike, it doesn't make me want to see him with my heroine. It makes me want to see him along side my heroine, telling her how it really is, or even fighting along side Angel.
So the argument that Angel is dull and Spike is not and therefore Spuffy for ever doesn't work for me.