I've had sails form several makers of the many years. North Sails are the best in my opinion, but they can be a lil more pricey then some sail makers. UK Halsey are the best off shore sails that I've sailed, also pricey. In the Chesapeake a lot of sailors go to Ullman Sailmakers. They are very reasonably priced & have great service & attention to detail.
Their loft in Deltaville, Va. is the best, & they service all the big & small yachts in the area.
It really depends on your budget. You can order off the shelf, pre made sails for a standard C 30 from just about everyone. You pay more for heavier weight Dacron, more reeefs, more for full battons, etc. The pre-made sails are basic, similar in quality to the original Catalina weight fabric. Shop around online & pay attention to the weight of the Dacron cloth that you are paying for. Lighter weight cloth is good for light air, but will not last as long or hold up to heavy weather as well. Remember that if you have a roller furling that your genoa has to be cut specifically for it. My UK Halsey 135 Genny has a padded luff which allows it to furl up better with less bagging in the sail when partially furled. You will also have to pay extra for a U.V. strip to be sewn onto a furling jib to make it last. Shop around.