I don’t believe there is such a thing as a universally ‘best’ DMD.
It really is a matter of what suits the individual: the most effective for the least side effects.
If you want the most effective (and qualify for it), then it’d be something like Lemtrada, but the trade off is the potential for serious side effects. If you want the least side effects, then Copaxone would be my bet, or maybe even Plegridy; the trade here is in relapse reduction rate. But for somewhere in between, there’s Tysabri (again, if you qualify) or Tecfidera (which nearly everyone qualifies for).
Personally, I’ve had 4 DMDs and had bad side effects from 3 of the 4 plus one failed to work after a few years.
And now I don’t qualify for any. Neither would I take any due to the aforementioned side effects. (Different for each drug!)