Idea 1: Sorting crafting items by energy cost.
right now it is sorted by the shortest time, the lower the timer to the right, but now with higher tiers of items there are sometimes moment when an item needs for example 20 minutes to be crafted or 500 energy, while another item can require 10 minutes and 1000 energy, it could be also nice if that sorting on energy would put all fusions on the far back so 5 fusions that needs 5 minutes to be finished are not in the way for energy rushing other items that are at the end. the way you could switch those can be somewhere close to the Craft/Fusion switch
Idea 2: Making NPCs in the shop go only to the racks they actually care, for example why a Monk goes to a vertical Racks if he doesn't use a single item from that rack, examples like that are not many in the game because most heroes have at least 1 item they can use from any rack, but why not to make them a little bit more intelligent if possible ? 
Idea 3 (image 1): being able to remove all heroes with 1 button from the hero selection on quests, not really an important one but it could be nice if i could just take off all heroes at once (while it happens a lot for me on lcog) also it could be nice for an option to disable auto hero selection because in more than 50% of the cases i'm switching entire team that was suggested to me automatically for different reasons, also i'm not sure if that issue occurs only me but when i remove a single hero from selection it kinda freezes my pc for something like a 1 sec which only delays and annoys me even more
Idea 4 (image 2): a notification with a number of current tasks available to do, it can look a similar way the characters icon has with available heroes, just a little thing for people that forget doing these
Idea 5: claiming all rewards from events passes with 1 button, especially needed if you have Royal Merchant and you have 2x more button to click just to claim everything