Just my opinion from months ago when I was searching for a all day vape...(These are juices, not flavors, but will give you something to compare your diy stuff to.
Best Chocolate: Windy City Vapor "Double Chocolate". 100%vg thats spot on chocolate icing flavor and huge plumes of vapor...
Double Chocolate - Windy City Vapor - E-Liquid
Best White Chocolate: Vapor Bomb "White Chocolate". If you close your eyes on the exhale it tastes exactly like you just took a bite of a Godiva white chocolate bar.
White Chocolate E Liquid
The two flavors that I used too recreate the above juices...
Perfumers Apprentice - Double Chocolate (Clear) Flavor <This one is a very clear colored flavoring that really helps if your using cartos... 15-20% flavoring is where I found the best taste (for me).
Perfumers Apprentice - White Chocolate Flavor <Also a very "clear" colored flavoring. About the same % was used as above to duplicate Jerry's VB White Chocolate taste (for me).
As with all flavors you may like more or less flavoring as myself or the next person...