I go by functions and temperament most often, especially the former. VI has it's place but I wouldn't type someone based on it, it's more like a vague indication
IMHO if one is going by the classical understanding of the information element descriptions (Model A) it's the most helpful way of seeing a type outside of the personality stereotypes that may be associated with them and their quadras. They explain the basics of the subconscious without overtly boxing every tidbit in
Other methods such a Renin, subtypes, and many of the user created systems may or may not have their place in being realistically applicable, and I've dabbled in some with half-seriousness, but I feel all in all that they're far too categorical and
for me to latch on to so I don't place a lot of confidence in them.
They, essentially, are meant to explain humanity into precise, systematic, categories that are meant to label the complexities in humans that are too complex to be labeled