We had both for several years. In the end however, we decided to get rid of the GFDs for several reasons. Yes, they are very cute and pretty, but after hours spent cleaning shitty bums they lose their appeal! Then they never really seemed to thrive here in West Wales, weather was too wet for their fleeces which simply matted over the winter. They are easy to handle, laid back and (generally) good mums, but are pretty high maintenance (we always had to dag and crutch a lot and then clear fleece to allow the lambs to find a teat). Ryelands (we had coloureds) put weight on faster and were generally more robust, with lambs that tended to be more vigorous. The trouble with the coloureds is the wool is practically worthless, unless you are going to shear and spin it yourself. We still have coloured (a few less than we did) since there is a good demand for lambs but brought in Angora goats for the value if their fibre (£15 a kilo!!! rather than 8p per kilo).
For a beginner I would recommend Ryelands over the GFDs - the latter are a bit like Valais Blacknose - incredibly cute but a lot of work.
As a final point, compared to some (not all) other pedigree breeds the GFDs are quite expensive and the market is dominated by a few breeders and limited bloodlines.