Thats a hard question to answer... Though they share some traits (i.e. a strong bass and a bit weaker midrange, the TMA-1 has the edge in clarity I'd say. That might make it prone to sibilance if the recording is harsh -- something the M-100 would not do I guess. Thats pure speculation though as I had no problems in that regard so far, but I used them only with EDM of various kinds. Rock might not be the genre of choice for the TMA-1 -- but the M-100 does not excel there either as I've read.
Comfortwise its a tie... both are not completely around-ear, the pads of the TMA-1 are much softer and I had no problem wearing them even these last rather warm days. The M-100 gets me sweating a bit but on the other hand their build and pleather cups seem to be more resistant (i.e. just wipe them off). The TMA-1 is astoundingly light and, in contrast to former variants, the headband has a nice cushion now.
Mobile use is somewhat better with the M-100 as it folds up and its cups are a bit smaller (i.e. easier to wear around the neck). Both sound good and go plenty loud with mobile devices, with the TMA-1 having a slight edge in efficiency.
Currently I enjoy both of them -- and I'm glad I don't have to decide which one to sell ;-)
So which one do you think wins in midrange? I like the look of the M100, but the Aiaiai is sooooo much cheaper, and if they can provide better sound, I'm gonna go order them.