I have been using IA for some time myself and am very pleased with what it offers, as a result I have a huge collection of items and only use one mule for trading purposes.
I see GD stash coming up a lot in conversation though, the interface looks nice and the crafting options (cheat?) seem enticing as well.
On the other hand I very much like the look and search function of IA.
I use both mostly. Only started with GDStash recently, had GDIA much longer. Since I can copy stuff into the Stash that’s what I do then put the stuff into the 4th inventory bag for GDIA to loot later on.