Why on earth does the best in slot sim suggest stat combinations on legendaries that are completely wrong? So the best in bags sim shows that the top dps/heal/mitigation of my spec has 0 versatility and 0 haste, so why is it telling me to put haste and versatility on my legendary? The amount of times i’ve wasted precious gold having to remake a legendary after realising that this service i paid for is about as reliable as a crackhead.
I would need to see your specific case to respond.
In general, best in bags is a localized max based on currently available gear. That solution may have somewhat different optimal stats than a best in slot solution, which is an absolute max (based on your setting/constraints).
Using the stats picked in Best in Slot or the legendary upgrade finder will more often lead to you crafting an item that is optimal once your gear converges on best in slot. It isn’t possible to know for sure, since the random loot gods may never give you a fully best in slot set of gear. We are trying to give you the highest probability of having the best stats on your legendary item down the road.