Which gear would be Good
I would either buy armor from the trading post every 5 -10 levels or craft your own at around the same frequency. There’s no point in investing too much in level 1-79 gear because you’ll pretty much be shedding them as you progress.
As for what in particular you should get, that would depend on what build you’re running right now and how comfortable you are with it. For instance, if you feel like you hit hard enough, but are squishier than you’d like, buy gear that will boost your toughness or vitality. If you feel like you have no trouble surviving, buy gear with more stats in power, precision, and critical damage.