Rootbeer is almost always a winner. A simple trick when using soda extracts, mix the extract with water and sugar in a 1L plastic bottle and store it in the fridge. To make 2L of soda, put 1/2 cup of the syrup in a 2L bottle, add 1/4 tsp of yeast and fill.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk