You can use any herbs that you like. I prefer heavy on the dill, with a good dose of fresh mint in there. Some folks like flat leaf parsley as well. Tzatziki is actually better is made the day before you plan to serve it, which gives the garlic time to infuse the yogurt.
Serving and Storage: Tzatziki is even better served the day after it’s made, so plan accordingly. It can be made up to three days in advance.