With the qualifier "If you had to vote today," I voted not guilty/self defense.
That's my vote based only on the preliminary facts/evidence we have at this point. However, IMO it is premature to vote on this, because there is not enough information to consider, to come to a reasonable conclusion yet.
Agree with gxm -- way too much reasonable doubt at this point. ICBW, but IMO the prosecutor overcharged. Just not seeing 2nd degree murder, no matter what.
If there is evidence proving that GZ lied about what happened, or that he acted improperly wrt the fight, or that LE illegally colluded with him to create a better defense, I would consider changing the vote to manslaughter if the facts lead that way.
As for SYG, IMO that is a possibility. However, due to the public circus and media frenzy, and the shakiness of SYG in the public opinion arena, I'll be surprised if GZ is given immunity from prosecution. The political and public pressure may end up driving toward a trial.
IMO there is much that remains to be seen.