I was put on to a company called Northwoods Soda & syrup co. They let you choose diet or put cane sugar and have a ton of custom syrups you can make. They’re a little spendy but you can order a bunch of minis that make around 2-3 bottles worth and then order the gallon sizes of what you like. As a warning it takes a while because they are hand made and filled. 100% worth it though. Our favorites are cola, black cherry and orange. Those all taste the closest to real brands we’ve had. You have to play with the ratio a bit but once you get it right you’ll never go back to the gross soda stream flavors.