For roasted barley, I use mostly Muntons and Simpsons for stouts and Thomas Fawcett for a small % in porters. The TF roast barley has a rather strong smokey flavor, which can be nice in certain styles. As for chocolate malt, Thomas Fawcett (330L) is my favorite and I use that and their pale chocolate (200L) for everything. I'll often blend them with the roast barley, although in a beer with lots of specialty malts, its hard to tell the difference.
Breiss' roasted malts are ok and they have both 6 and 2 row varieties. Their crystal malts are rather grainy and bland for my taste. For crystal malts, it is hard to beat Simpsons and Thomas Fawcett. Cheers.