In "The Tyger," is the tiger portrayed in a negative, positive, or neutral light?

The tiger in Blake's "The Tyger" is presented in such a
way that none of the choices you offer--negative, positive, or neutral--really
fits. 

"The Tyger," from Songs of
Experience, and its companion poem, "The Lamb," from Songs of
Innocence, present opposite sides of the same existence, opposite sides of
the same creator, and opposite perspectives of the same existence.  Thus, the tiger is
not negative, not positive, nor neutral--it just is. 

Blake
did not believe in dichotomies; he did not believe in good and evil in the traditional
sense.  The world is not simplistic and neither are people.  Existence cannot be labeled
or categorized.  Human beings are not completely good, or completely evil, and
neither are the creator or nature.

The lamb represents
innocence and an innocent perspective.  The tiger represents experience and an
experienced perspective.  Neither is good or bad,
or negative or positive--the lamb and the tiger just are.  That's just the
way it is; that's existence. 

Furthermore, the same creator
that made the lamb also made the tiger.  And if he can make two creatures so opposite,
then the opposites that exist in the creatures, must exist in the creator, as
well.

Look at the reverence and awe revealed in the stanza
that opens and closes the poem:

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Tyger, Tyger, burning
bright,

In the forests of the
night;

What immortal hand or
eye,

Could frame thy fearful
symmetry?

The tiger burns
bright in the forests at night, and it takes some kind of immortal to create this
beast.  But there's nothing evil here.  A tiger isn't evil.  A tiger is a predator that
kills to eat.  Tigers don't kill for fun, people do that.  The tiger is presented with
reverence and awe. 

Also, the "Did he who made the Lamb
make thee?" line is a rhetorical question.  The line is the conclusion to everything in
the poem that's come before it, and makes the point that yes, the same creator that made
this fearful beast also made the lamb.  That is the
point. 

Just to be practical, if your assignment requires
you to choose between the three choices you mention, I'd suggest using
positive, even though, again, the tiger is just a fact of life, or
of existence.  But positive is certainly more accurate than either of the other two
choices.