I’m a firm believer in good quality balsamic vinegar, something that has been aged at least 10 years but preferably longer. They can get quite pricey though so I keep at least two kinds of balsamic at home. I’ll buy one that is $30 or more for about 8 fl oz, used to finish dishes in small amounts. These are thick and syrupy and just a few drops with an equally good extra virgin olive oil is all you’ll need to turn a salad into a restaurant quality starter. I also buy the big bottles at BJ’s or Costco, a regular commercial brand that is around $7 for 34 fl oz. These pour with a viscosity similar to water. This is the one I cook with or use to make dressings that I’ll be mixing with more ingredients.