Like any instrument, choosing a guitar is subjective so any musician will have their favorite brand or model.
As Mario suggested I suggest looking at guitar brands and models that are known for their nylon string guitars. While Gibson, Martin and Fender are the best known and copied American brands their strength is steel string guitars, not nylon string guitars so for that reason alone I would favor other brands. Also, Flamenco guitars differ from "standard" classical guitars by having a thinner top and less internal bracing so the list of manufacturers is likely reduced even more.
Do an internet search for the names of current and popular flamenco guitar players.
+++ HERE +++ is a good starting point. Visit their websites to see if you can find what guitar brands and models they endorse. Look at their publicity photographs to see if you can figure out what brand guitar they are holding in the photos. See if any of them have any namesake guitar lines.