The quality of chocolate you use will be the primary determining factor of how your finished chocolate candies taste. Chocolates are not all created equal, and in general, there is a strong correlation between quality and price. This is not to say that you should always buy the most expensive chocolate, but be aware that high-quality chocolates with large amounts of cocoa butter and cocoa solids will cost more than their inferior counterparts.
Selecting chocolate should primarily be a sensory experience. Before you taste the chocolate, look at it closely. You want chocolate that has a glossy surface and is free from blemishes. If the surface is scarred, cloudy, or gray, this may be a sign that the chocolate is old or has been subject to extremes in temperature or handling. Next, break the chocolate in pieces. You want a chocolate with a clean, hard “snap” to it. If it bends or crumbles, either the quality is low or the chocolate is old.
Good chocolate will smell strongly of chocolate. Rub your fingers over the surface to warm the chocolate, and then smell the bar. If it doesn’t smell like chocolate, or if it smells primarily of vanilla or other added ingredients, it probably won’t taste very much like chocolate either. Chocolate easily picks up odors from its environment, so be aware if your chocolate smells like coffee, tea, or other aromatic foodstuffs.
Finally, taste the chocolate. Pay attention to the way it melts in your mouth: does it feel waxy? Unpleasantly chewy or dense? Does it leave a slightly slippery feeling? Does it feel sandy, or smooth? In general, a smooth, velvety mouthfeel is preferred. Also notice what flavors you can find in the chocolate. Common descriptions of chocolate notes include floral, citrus, berry, coffee, and wine undertones. Notice if the flavor bursts out all at once, or if it gradually builds in intensity and lingers after the chocolate has left. Above all, trust your own tastebuds. Chocolate preference is very personal, and you know what tastes good to you, so select chocolate that you will enjoy eating.
There are many, many different brands of chocolate and chocolate manufacturers to choose from. Names to look for include: Belcolade, Blommer, Cacao Barry, Callebaut, Carma, El Rey, Felchin, Ghiradelli, Guittard, Lindt, Scharffen Berger, Valrhona, Van Leer, and Wilbur.