It's a give and take, I have tried most of the iOS DAWs, if not all, one needs to pinpoint ones main needs, and choose based on that, there is no holy grail unfortunately (reservation for Logic that I have, as mentioned, not tested as it was released after I gave up and went with a Surface + Studio One instead).
N-Track was one of the most "complete" when it came to the more complex advanced things, like tempo, sync, etc. but was not that great in general workflow etc. (imho). I think it was the built in metronome that could not be routed to anything else than master out, or if it was just added to all outputs (used an interface with many outs), or something like that, which was pretty annoying and incomprehensible, among things.