i would chose sebastian and ciel, but my taste would be alois x claude! i can tell, although it's hard to believe, that they are going to have a deeper relationship! and plus, i give another point because i juss 愛 the new characters a little もっと見る than sebby and ciel. ALTHOUGH I 愛 the first season's characters,too! :)
I think it has to be either Sebastian x Ciel または Alois x Ciel. Since the マンガ was originally supposed to be a やおい in between Sebastian and Ciel, I think almost everyone ships them. I admit they are one of my OTPs. But, still, there's the whole bit about Alois going after Ciel and being all I-want-you-Shieru-chan. That can't be overlooked. Ciel and Alois is shota/shota, while Ciel and Sebastian is shota/seme, which is equally as good. I think they tie, and aside from that: If I had to choose a pairing that's canon, it would be Sebastian x Ciel.