I'd like to say Jast, but their timetable leaves me questioning how serious they take the business - if it's a side project for them, or a fulltime thing~
MG is starting to show promise, I hold them in waaay higher esteem compared to what I used to think of them, in any event. So far the most professional appearing. (never met them live though, at a panel - I've heard mixed stories).
SP...well, not to start a hate parade...I have/had hopes for them, but they still often behave like the Mirc clique they rose up from, and tend to mouth off and behave with a lack of professionalism, seen as antagonistic - not very appealing. Time will tell though, hoping it's just growing pains.
I want to say MikandI, because I like their style - but that's still miles off, and heavily reliant on future sales (and how vested their interest is in continuing to pursue the market).