Picked up 19 random DVDs I hadn't seen from a going out of business sale. What should I watch first?

District 9 would be my first recommendation. Haven't seen everything on the list, but from those I've seen I'd say The Hangover, In the Loop, 500 days of Summer and Public Enemies are worth watching. On the other side of the scale is Knowing, which I thought was dreadful.

District 9 is good, but it's an easy-sell. 500 Days of Summer is much better. 
 
Let me know that 'Fighting' is the worst film ever made.

District 9 and Street Kings are the only two movies on that list I have seen and liked.

Not sure how much you paid but you got a great select of DVDs :-) I'm recommending In The Loop because I am British but if your not British i'm not sure you will get any enjoyment from the film. 

" District 9 and Public Enemies "

500 Days of summer is a fucking awesome film, i was very suprised by how much I enjoyed that.
 
Also, never watch the invention of lying... simply burn the disk you'll do humanity a favour.

I almost fell asleep during Public Enemies.  The sound quality was terrible and NOTHING HAPPENED for the first 90 minutes.  It was at that point I said no more and took it back to the rental store.
 
And I was pumped for this movie since it was shot in Oshkosh, WI (I'm from Menasha which is really close).  The coolest parts of the movie to me were picking out landmarks I knew.

500 Days of Summer! Watch it, and be amazed.

Fookin fook mate.

I voted Public Enemies... but it should definitely be District 9.  That movies is really really awesome... and I would have voted for it if I had scrolled all the way down first. >.<

 District 9

In the Loop is hilarious, although some of the humour may be lost on you if you're not British.

(500) Days of Summer is the bomb.  Then The Hangover, then District 9.   I think I'd consider all 3 classics.

OH GOD, TUNNEL RATS IS AN UWE BOLL MOVIE!!
I think.

the obvious choice is district 9. knowing isn't that bad as well, but I'd watch other movies on this list before it

500 days of summer is the best on the list then Ninja Assain is also good

Hangover.

B.

District 9, Funny People, 500 Days of Summer, Invention of Lying, The Hangover, Away We Go, In the Loop, Public Enemies. 
 
All quality. The rest? Not so much duder... not so much.

The Hangover 
Fighting wasn't bad, A little slow but not bad.
Everyone is voting district 9 but I was really unimpressed by it, Which sucked because I was really looking forward to it.

I'd watch all the garbage ones first.

In the Loop is one of the funniest movies I have ever seen.

district 9 is one of the best movies in recent memory, imo