Photomatix and Nik HDR Efex Pro 2 are the two best ones IMHO.
However, Photomatix is not intuitive in the slightest and you can often get lost as to what to adjust and what not to adjust. Nik is far simpler to use and gives great results.
However, both introduce noise - sometimes too much. Ideally, you would be better to do exposure blending to ensure noise is kept to a minimum. In all cases though, less is better - avoid the high saturation effects like the plague, and go easy on the sharpening.