Which primarchs do you currently want to come back badly?

Depending what primarchs you want to return, how much of an impact are they to the current imperium if they came back and how can they help the imperium or support Guilliman? For me, I want Vulkan to come back. The only missing primarch I know that could come back is Jaghatai khan cause I just imagine if a fast-as-fuck guy like him goes to another dimension where there's a lot of space, he'll act a little goofy and just start running to the point where he probably explored most of the warp lol