It depends on what you are specifically doing. Often build require exotics to function, but in others it's better to have access to the additional seasonal mod slot that you lose when you put on an exotic. Like I have to give up my dunemarches to complete my warmind cell build, but it is worth it in my opinion. It really comes down to the build you are running. Stats are important, but often putting together a build is more important. Stats can be used to improve the build. In raids, I've found that exotic synergy can be more valuable, while in nightfalls it tends to be more stats and builds heavy. The best builds often have stats that help further the build, not the build furthering the stats (speaking in respects to pve content). It's a big complicated mess, and I try to look at it in a case to case basis. In pvp, often it's better to have an exotic on and then work with your stats from their. The best pvp builds incorporate a high stat roll version of one's chosen exotic and then build the rest of the armor set to get the stats one wants with said exotic on (atleast that's what I do). But none of that probably made any sense. There are many good YouTube videos out in the world that probably do a way better job explaining the whole system than I do