I really like Drumjam as it works to fill a number of different uses and it’s on the bus!
Useful for live feel drums and percussion loops, help in creating your own loops and fills, and a drum sound source. If there’s a downside it’s the shortage of electronic kits.
Definitely worth a look but make sure you know what it does before buying.
Seems slightly ironic that the best sounding drum resource on iOS, iMaschine, has been specifically built not to Iet you use it with anything else in the iUniverse… 