I live in Kent, about an hour away from London. In case you're reading this in what you perceive to be my voice, I'll try to explain my accent, 'cause most people'll assume I'm either ridiculously posh or proper "Laaaandaaan" Cockney. I'm not either. I probably speak sor' of like this, which is kindov like Cockney, bu' my accen's more posh like from London, it's just become a habbi' to leave of some endin's and random letters. Anyway, now we've got that sorted xD
I quite like the New York accent. My geography's awful so I'm not sure where NY is, but if I'm right it's somewhere in the middle-top part. Somewhere... :P And if I'm right, then the NY accent is what they speak in programs such as 'Friends' and 'How I met Your Mother'.
Canadian accents are okay, too. The "Aw HELL naw" accent just makes me laugh, it's quite nice to listen to though... In small doses;) There's only one accent I absolutely can't STAND, which is the Texas, down South, "horse riding, country-singing, Hannah-Montana" accent. It's beyond awful *shivers*.
I'm really sorry, I'm just being honest. That's only my opinion, and just because I don't like the accent doesn't mean the people can't be wonderful and very lovely, so please don't take what I said personally.
And I know you only asked about North America, but I thought I'd cover it all, 'cause as I said, my geography's really, really bad. And I'm sorry if I missed out any vital accents that "everyone knows, duh!". But it has to be said that often one of you guys'll forget that over here we have Welsh accents... And West-country... Yorkshire... Northern... Liverpudlian... Birmingham... The list goes on ;)