There are many previous posts in this thread re the missile vs fighter theories
Most all re fighter have been debunked.
There have also been posts re the typical buk missile flight profile which seem to summarize as follows
a) very high speed M= 3 plus
b) very high altitude capability 70 to 80 K feet
c) flight profile via radar and proximity mention the missile typically leads the aircraft,
dives on it from a higher altitude and explodes via proximity and/or contact
d) left side Cockpit damage AND shrapnel " skid' marks on left wing UPPER surface indicate that missile was at at wing level or slightly above when detonated
e) not so obvious is that almost any kind of ' corner' angle of aluminum makes a good reflector- consider the wing to body junction for instance
f) U.S tracking claims it was a missile
ALL of which support a missile from a general head on position.
g) what remains to be proven is WHO and WHY fired.