Go for SPD til you hit 50% SPD. Rest is up to you. For now Iam quite fine with all in DMG, cuz 45% crit rate + 15% from Meteor mastery equals 60% on level 75 monster. Since all mobs except IA/WA/SkyTower are lower then 75, your real critrate is higher. Going DMG also increases your defence, when using The Best Defence Mastery.
Try to get your defence somewhere between 65%-75% and put the rest into HP.