An iPad is the centre of most of my music making these days so I thought that I would offer my thoughts.
AUM is absolutely essential, so much so that I can divide my music making with the iPad into Pre AUM and Post AUM eras.
Anything by Apesoft/Amazing Noises is great and pretty much every parameter in every one of their apps can be automated with LFOs. In my opinion Dedalus is more versatilel than ApeDelay, but they're very different and both worth having.
And as others have said Borderlands, Samplr, the AUFX bundle, and Fieldscaper are all brilliant for processing guitar or anything else.
Here are some short examples of some stuff I have made with my setup. All of these are just classical guitar and iPad, all improvised and all live with no prerecorded samples or loops. All played and recorded in AUM.
Borderlands and sidechain compression from AUFX Push
https://www.instagram.com/p/BacN5GBnl2p ... nbridgland
Lots going on here...a lot of Moebius Lab...I think...
https://www.instagram.com/p/BY6ei_gnxzX ... nbridgland
All Borderlands I reckon.
https://www.instagram.com/p/BY8zz4cn7Et ... nbridgland
I'll be honest, I can't remember where this noise came from...
https://www.instagram.com/p/BY_jNbSnD8Z ... nbridgland