I've had a Roxio Game Capture HD Pro, which already stopped working after about 6 months. It also records it's video in .m2ts format, which couldn't be imported directly into my editing software without converting it to a .mp4. Although the quality was good, and it was easy to setup/use, I wouldn't really recommend one because of the 1st two points I made.
I've now got an Elgato Game Capture HD. I think it's very good! It's small in size, easy to setup, looks slick, the recordings are good quality, the capture software is easy to use, and records it's videos in .mp4 so can be dropped straight into Vegas. I would definitely recommend one!