Image file formats?

This morning, the topic of image file formats came up when I discovered the final image sequence for one of our spots was rendered as PNG files. I asked, "Why did you use PNG?" and got a response, "Why shouldn't I use it?" I didn't have a good answer besides the fact that I've just typically never seen it before.

So I looked into it, and PNG uses lossless compression DEFLATE and supports 16-bit integer out of AE or Nuke. My test file sizes also tended to be smaller compared to 16-bit TIFs or SGIs, which are the other formats I've typically seen used in my experience. Artists also say that it's faster working with PNG sequences as opposed to TIF.

What do you guys use for things like final image sequence archives? Depending on who's doing it and alignment of moons, we have anywhere from PNG to TIF to uncompressed Quicktimes. What about interchange between different applications? From 3D to 2D we use a lot of multi-layer EXR and TIF.. sometimes PNG for mattes. From 2D, it's mostly TIF and PNG... DPX if we're working with footage. There's been a lot of "that's just the way we've done it" so I wanted see what others are doing, and lock down a spec.

Thanks!