Pre-made ejuice, or flavors for making your own? Do you like Virginia tobacco? That's the only one I've really liked a lot, though I don't really anymore. MyFreedomSmokes.com has a great Virginia ejuice; for DIY flavors, I found the Tobacco Express Virginia very good, with just a smidge of Bitter Wizard to keep it from being sweet.
If you prefer sweet tobacco, and/or high VG, then Long Bottom Leaf Pipe Sauce is good; like walking into a smoky coffeeshop back in the good ol days when smokers didn't get chased outdoors by all the ANTZ. Sweet tobacco, bittersweet coffee, and a trace of a choc and vanilla flavor.
Andria