Matroska! Because it is versatile... Takes almost anything...!

How about Mp4? How is it compared to MatRoska?

a choice? : whatever works for a specific purpose, usually its avi for editing, mp4 for web (proof) delivery.

AVI definitally.

I dont see the use in anything else. I tried taking one of the DVDs I backed up and encoding it with x264 and matroska, and it didnt play, even though I had the x264 codec thingy installed. Sure, I could work and find out how to play it, but I didnt want to take the time. XviD in .AVI is fine.

I voted AVI

Matroska instead of AVI because it's so easy, I don't have to worry about anything.

Matroska instead of MP4 because I don't own a DVD player, I don't own an iPod Video, there's hardly any standalone player out there yet that can play standard MPEG-4 AVC videos (or am I wrong?)... Well maybe in the future I will switch from Matroska to MP4 when buy a standalone player, but at the moment Matroska gives me the best freedom of choice when it comes to Codecs and several Audio/Subtitle streams.

Matroska. Very versatile accepts anything from Subs to multiple audio streams to Chapters. I only watch videos in the laptop or connect it to the tv using tv-out so i don't really care about "lack of compatibility" with certain boxes.