Hi hairadv,
Hasson and Wong have been Pioneers in the field of hair transplantation.
They were the first to do "mega-sessions" on a consistent basis.
The main reason I chose Dr Wong is because he was the creator of the Lateral Slit Incision.
Many of the top hair transplant surgeons have trained with Hasson and Wong or adopted their techniques, which speaks for itself.
I believe the Lateral Slit Incisions allow Hasson and Wong to dense pack more efficiently and it causes less trauma to your scalp, which allows for faster healing.
H&W obviously have been using this techinique longer than any other clinics, so I felt the most comfortable going with the guy who created it.
Browse their website and videos. I think their results speak for themselves.
Good Luck!