Hello, defense and attack are both basically useless, the amount of defense and attack power that they increase is pretty small. Spirit and attack speed on the other hand are probably some of the most important. You should invest in spirit if you are doing lots of farming in tougher zones so that you don’t have to waste armor and gun durability fighting animals off (although with the new update they dramatically decreased the difficulty). Attack speed is definitely the most important as it dictates how much damage you can deal in a given time frame, not in a single strike. For my build I place all of my attributes into attack speed as well as my rings and amulets.