I don't know how much of a quest you want to make out of eggnog; or, which eggnog concentrates you already have on hand. But, of the three brands I have (TFA, CAP, and LA), LorAnn's (LA) is hands-down the best to my taste buds. It works as a stand-alone (5-6%), and can also be easily boozed up with a rum, brandy, or even a whiskey. It has a nice thick eggy mouthfeel, that is not too heavily spiced (but it is there), and just a suggestion of booze. As a stand-alone; it reminds me of a dairy-made seasonal grocery store offering.
It is kind of hard to find these days. The only site that I routinely shop, that still offers it, is
Nicotine Giant. BCF, NR, WL, and ECX no longer seem to offer it (of those that did).