The mystery surrounding the disappearance of Malaysia Airline's flight 370 has produced much speculation, guess work and conspiratorial theorizing. However, in the absence of hard facts, the age-old principle of Ockham's Razor (sometimes Occam's Razor) perhaps should be applied. This established principle of problem solving maintains that with the absence of factual information, the simplest answer that depends on the fewest number of facts should be used, until proven otherwise. Of course, this does not drive viewers or traffic to TV cable news channels or websites respectively.
One of the best theories I have read relies on what was currently known at the time of it's publication, and upon the experience of the author. To my knowledge, this still appears to be the best/most likely answer to this horrible event. It was first published on Google Plus (then Wired) by Chris Goodfellow. The basic premise is that of an electrical fire, followed by an attempt at an emergency landing at the nearest suitable airstrip. The article is convincing, explains a lot of the known facts, and fits with the Ockham's Razor principle.