How? Let alone "Why?". Motive and opportunity.

Cause the pro Russian separtists are most likely the ones who shot it down and where else would they get such an advanced piece of military technology? Also Russia is suspected by many experts. 

I feel sorry for Malaysia airlines. Losing 2 planes and now their reputation would be completely damaged by this.

At 10km altitude? With what? A slingshot? And what are their motives?

We don't know anyone's motives. Its just a possibilty. Who knows though? Maybe it was Ukraine and USA that planned it in a way so that Russia would look bad. Who do you think did it? 

I've already said what I think, a tragedy as the result of Ukrainian army actively playing with dangerous toys without precautions (not for the first time btw, remember that Tu-154 from 2001) provided the plane indeed was shot down. No one else in close proximity could have done this, unless we're going into too much of a conspiracy stuff.

Blaiming rebels is a stretch. I've already said that the only SAM they have, that could have done this is Buk-M1 they've captured from Ukrainian army (there're documental evidence to that including their own claims and photos), but here're the problems:
- they are most likely non-operational (their own claims and they indeed never used it);
- if they operational, what rebels have are 1 or 2 missile launcheres, while a single operational division (зрдн) consists of 6 launchers, 1 command post, 3 reloading machines and 1 tracking and target designation radar, which feeds data to launchers, -- at the very least to successfuly fire a missile they should have at least one radar (this thing), which they don't
- they need trained crew, which they don't have

Blaiming Russia is a stretch because Boeing was in sight but out of reach for Russian air defence.

While blaming Ukrainian army is easy, here're Buks, plenty of them, seems operational (see 0:53), video from July 5th:

I'm sort of agreeing with your opinion but you're leaving out the possibilty that Russia supplied the rebels with all that equipment. Afterall, the rebels did shoot down 2 cargo planes last week. 

Having said that, I agree with you that it was not Russia or ther rebels that were responsible. 

I can't see the video unfortunately. Could you post the link? 

Well, for that Russia should have supplied Buks with a crew as well, and it doesn't explain motives (9 chances out of 10 the incident will be blamed in Russia publicly regardless the investigation). Nah, I'd trust Occam here, unless proven wrong.

Il-76 was shot when nearly landed if that's what you mean. First An-26 wasn't cargo, it was artillery observer plane that went down for that purpose a bit too low and was shot down. The most recent An-26 was cargo, but I'm not sure how it was shot down. 4km altitude is what rebels could possibly afford for now.

Yeah, the blame on Russia thing is why I think you're right. The media is hardly considering that anybody other than Russia or the rebels was responsible. That makes me think that USA was involved in this with Ukraine. 

It's not going to be a false flag operation. I really don't think Russia would be dumb enough to do this (Soviet Union learned before that gunning down passenger aircraft is bad news, KAL007 and all), but Ukraine's not going to do something like this deliberately, not when they have the Separatists on the ropes.

Two best explanations are Russian agents assisting the Donbas separatists in using the Muk, the Separatists getting really (un)lucky with firing the Muk, or the Ukrainians having a similar bout of bad luck (though why they would fire on a plane headed eastward...)