Badlands is my favorite, but Days of Heaven is by far the best of his works. The Thin Red Line is well done but it didn't do anything for me. I've watched it several times and am amazed and bored at the same time.
Badlands is great....True Romance is basically a Badlands rip off.....they copied the music as well. True Romance, although it's enjoyable in a sort of superficial way, doesn't pull it off. Badlands on the other hand, is great. Among many other things, it has the character development that True Romance skipped, and it goes a long way.
Malick is one of my favorite directors. Many seem to think that in order to be considered a great director you have to produce a bunch of consitently great films. One great film and everyone is anxious to see if you're a one hit wonder and just happened to get lucky. If your 2nd, 3rd, and 4th films suck...in many peoples' mind, you suck and the 1st is considerd a fluke.
Those of you who have attempted or made a film, of any sort, know how difficult making a solid film is. In my opinion, if you pull it off just once, that's enough for me.