I’ve used iThoughts for quite a while; my Scapple lieutenant (it reads Scapple files) for iPad.
It suddenly got even better this week as it now has a very nice outline feature.
iThoughts is my preferred visual organising tool. I’m glad to hear Craig is continuing to improve it. 
Another shout-out for iThoughts. My favourite mind mapping app. The fact it reads Scapple files is triple bonus.