IMO there's no such thing as a good Collada exporter/importer.
Yeah. I've found there's one standard worth using and it's fbx. All the others are deficient in one way or another. They don't include camera, they allow too much variation, they don't have bone animation, etc, etc. It might not be open source, but it's open enough and it works. Blender is horrible about keeping up their exporters. They don't seem to care if they work or not. The md2 has been broken since version 2.30. I know a lot of people that would still like to use it. It comes in handy. But I'm pretty sure this is Google because I tried a free convertor from whoever makes fbx, can't think of their name, but it just showed an empty model when I imported it converted to obj. It was just a simple model, too. Some of them work, some don't. The dxf seems pretty consistent.