It would be fun to create your own provided the syrups taste real and not too artificial. Some flavors are really tough to recreate. I would start with a vanilla/cherry combo .. my favorites.
The more things change the more they stay the same...
Back in the 50s and 60s you could go to any soda fountain and ask for a vanilla coke or cherry coke or... etc. The combinations were up to you. Chocolate coke was a personal favorite.