OBJ also carries the UVmap just fine.

right now, it's the best of the 'base' formats for moving things around. it's well established, understood and tested.

Collada still needs to mature. it's not universally accepted as yet, while you can find many apps that export it, only a few import it and then success can be problematic.

I'm not anti collada at all btw. I just think it's still in it's very early stages and has a long way to come.