Hmm, interesting one. I voted Hotel Chocolat, because it's very high quality and I've never had a bad choc from there; I even tried the coffee ones in a selection I got and they were edible (which is a high compliment from me when it comes to coffee!) But I think they all have their own good points, with the possible exception of Nestle. Cadbury is my favourite in a way too, even though it's not strictly 'the best', because I've grown up with it and know I'll enjoy it.