The Pioneer's seem to be the most popular.
AVH-P3200BT (needs a separate GPS module)
AVIC-Z130BT
Touch screen car stereos have not really changed in the past 5 years and are mostly still using low resolution resistive touch screens. Hopefully they will take a page out of the tablet market and make a better product.
However, as far as the best navigation unit I would still vote for the Samsung Galaxy Tab. It can be had for under $200 and is far and away the most versatile option so far (Netflix, Plex, OBD2 scanner, Music, Movies, Nav...)
Mount it in the Nav Pod, or have a bracket made for it and use the stock stereo or any one you like the look of (I like the JVC 810 personally).