Wizard labs is my favorite place to get flavorings. Only downside is that since they moved locations, they've been a little slow and out of stock. (not sure if they had the stock issues before they moved, as I'm a recent buyer)
My favorite tobacco flavorings are (all purchased at Wizard Labs): RY4 double (TPA), Captain Black (Seedman's), Black Honey (TPA), RY4 (original) (TPA), and Commerical Tobacco (TPA)
In my experience and vape preference, the RY4 double, Captain Black and Black Honey can be vaped right away, while the others are best when they are steeped.