The general consensus seems to be:
MH370 = unknown
MH17 = accidentally shot down by pro-Russian rebels
Taiwan plane = typhoon/weather
Algerian plane = weather/thunderstorm/lightning strike?
None of them seem to have been caused by a technical fault in the actual plane (i.e. from shoddy maintenance) but were instead caused by forces outside the plane's control.
So 3 of these are pilot error, if you include the one shot down as pilot error for flying over a hot war zone.
Given the facts about MH370, we lean strongly that it was action by pilots, if not "pilot error".