I didn't know Buffy and Spike had such a large following. .
I prefer Spuffy over Bangel as well. Less angst, more fun.
Spuffy and Bangel have both had angst aplenty. The difference is just that Spuffy also has humorous and down-to-earth moments; Bangel, not so much. Bangel was always epic romance drama, Spuffy gets to mix different genres.
I did like Bangel back in the day (certainly not in season 8, though - oh god, no), but Spuffy appeals more to me because Spike and Buffy communicate in a no-nonsense way that I like better, and because the dysfunction is out there in the open, while the love and the deeper and tenderer emotions are mostly shown through actions and just hinted and left unsaid. Unlike Angel and Buffy who were always talking about their love and making big romantic statements, and where the deep dysfunction gets covered in nice romantic surface (Spike/Drusilla were like Angel/Buffy in that respect).