Quality means mostly a good story/production. Personally i like movies like Cloverfield, The Tunnel etc. It's refreshing in a "WTF is happening!!!" way.
I recommend:
Gwoemul
http://www.imdb.com/title/tt0468492/
(You wont get bored for sure on this)
Primer
http://www.imdb.com/title/tt0390384/
(You might get a little comfused on this)
127 Hours
http://www.imdb.com/title/tt1542344/
(Also a good movie)
Right at Your Door
http://www.imdb.com/title/tt0458367/
(This movie is one of my favorites, theres a Major Twist in the End.)
Resque Dawn
http://www.imdb.com/title/tt0462504/
(Also a good movie)
The Soloits
http://www.imdb.com/title/tt0821642/
(Good story, acting etc.)
The 5th Element
http://www.imdb.com/title/tt0377917/
(No matter how many times i watch this, i never get tired of it.)
I write down all the movies i like. I still have more. Pm me if you want something specific to watch.