I used this thread back when I was new to DIY. After collecting, experimenting, and vaping hundreds, I can make my contribution now.
best root beer - 5% Rasta Rootbeer by Tasty Puff
best cola - 3% Cola by FlavourArt (FA)
best Irish cream - 2-3% Irish Cream by FA
best dark rum - 2-3% Jamaican Rum by FA
best brandy - 2% Brandy by FA
best unadorned coffee - 2% Coffee Espresso by FA
best spearmint - 3% Spearmint by FA
best peppermint candy - 10% Candy Cane by Flavor West
best peppermint - 3% Peppermint by FA
best creme de menthe - 5% Creme de Menthe by Flavor West (FW)
best green tea - 3-5% Green Tea by The Flavor Apprentice (TFA)
best black tea - 3% Black Tea by FA
best honey - Honey by FA (under 1% as an additive)
best plain cream - Fresh Cream by FA (2% or less as an additive
best sweet cream - 3% Vienna Cream by FA (creamy sweet vanilla)
best sweet lemon - 3-8% Lemon Sicily by FA (this is Limoncello liqueur flavor)
best key lime - 4% Key Lime by TFA
best lime juice flavor - 2% Lime Cold-Pressed by FA
best blackcurrant - 1-2% Blackcurrant by FA
best black cherry - 2% Black Cherry by FA
best mandarin/tangerine - 3-5% Mandarin by FA
best maple syrup - 2% max. Maple Syrup by FA
best hazelnut - 2% max. Hazelnut by FA
best nutmeg - Holiday Spice by TFA (under 1% as additive)
best cocoa - 3-8% Cocoa by FA (dark baking cocoa)
best molasses - 3-5% Molasses by TFA (mild sweet molasses)
best brown sugar - Brown Sugar by TFA (under 2% as additive)
best and only meringue - 3-5% Meringue by FA
best and only marzipan - 3% Marzipan by FA
best and only torrone - 3-5% Torrone by FA (Italian nougat candy)