I agree that ADX is nice. It's one of my favorite formats (largely because of the looping capability). However, I think LOGG (VGMstream supports it) is better. That is, it's OGG files with looping data in them. They're smaller than ADXs, and have comparable quality. And, if you have a player that doesn't support LOGG (to my knowledge, VGMstream is currently the only thing that supports *.LOGG), just rename it to *.OGG, and it will still work perfectly fine (minus the looping. The data is still present of course, but since so few players support it, sometimes the OGG extension is the one you have to live with).
SquareTex: If you like ADX, you should give LOGG a try. It's very easy to add the loop data because it's stored in the OGG tags (similar to how MP3s have the ID3 tags). In other words, you don't have to encode/transcode to OGG/ADX just to add loop points. In VGMstream, HCS has even included an argument that outputs "oggenc.exe" compatible syntax so that you can easily transcode between various formats. It works great.
Anyway, as far as streamed game audio goes, ADX is the closest thing to MP3 you'll find. It's a format that is used on every console, and is easy to work with. It's even licensed, just like the MP3 format. :P But since developers apparently like to re-invent the wheel when they develop the audio format for their game, you still see a lot of variations, alterations, and custom formats. Maybe they don't want to pay the license fees? Mouser X over and out.
Mouser just a question, why is it called *.LOGG? Wouldn't it make sense just to call it *.OGG? That way players that have looping would play it looped and players that don't would play it as a normal OGG file. The Vorbis codec in Winamp is lower in the list than VGMStream so it would play *.OGG through the VGMStream, and it requires no extra renaming then.