Pick your level. Each slot shows the highest scoring item you can wear by then; open a slot for its top 10 with their scores. The best in slot planner adds your own weights and where to get each piece.
Score = each stat times its weight: Stamina 1, Strength 0.5, Intellect 0.4, Agility 0.3, Defense Rating 0.5, Dodge Rating 0.6, Parry Rating 0.6, Block Rating 0.4, Block Value 0.5, Armor 0.05, Bonus Armor 0.05, Spell Power 0.3, Melee weapon DPS 1.5. These weights are a starting point, not a simulation.