I don't really have any favourite brand that I'd use above any other these days. I sort of like different kinds for different workability. Faber Castell Albrecht Durer because their range of reds is astounding, and they have a comprehensive and lovely range of very dark greens and blues; but they don't apply as dark as you'd hoped. Derwent Watercolours because they have some really lovely shades (jade green, the turquoise green and blue, the water green, and so on), and because they have a reliable texture and output. Derwent Inktense for very vivid hues when necessray (especially in the reds), and you don't need much to get an amazing result.

So, a mix. :)