Just like with most ingredients, it always matters what quality ingredients you use. With that being said, you don't need to spend a whole lot of money (and it can be hundreds and thousands of dollars) on the best balsamic vinegar. There are three main grades of balsamic vinegar: Tradizionale (traditional) - it is the authentic balsamic vinegar that comes from the region of Madena and Reggio Emilia. This is the most expensive option because if it made in the original region where this vinegar came from following the traditional methos and grapes. It will carry "DOP" designation on the label. It is made with proper grape must and aged 12 to 25 years. This vinegar will the rich, sweet, thick and syrupy and there is NO NEED to reduce it. Industriale ("Balsamic Vinegar of Madena" or "Commercial Grade") - this vinegar is made quickly from wine grapes and aged very minimally if at all. This is where you will find the most variations because it's not strictly regulated. These are thinner, much more acidic, and not very sweet. Look for labels like IGP, aged, and choose those darker in color. Condimento (Condiment grade - these are negarally made outside of the regions of Madena and Riggio Emilia. These vinegars are inferior to any of the above and normally contain many ingredients to blend the flavors together rather than the grape must. This type of balsamic vinegar is not regulated much so you will find the widest range of quality here. Check the label, there is often added ingredients and sweeteners. You're looking for vinegar that lists only grape must or gapes.