PDA, mainly because you'll hardly ever use a handheld GPS. You think you will, but in reality you won't. So at lest it will be able to do other stuff.
When I purchased my airplane it had a panel full of 1970's state of the art avionics and a top of the line (for its time) Garmin 195 moving map GPS. The handheld was my primary nav means and the VOR's were rarely even turned on. Even before becoming an aircraft owner, I used an Airmap 100 handheld in rentals. Since the equipment in rentals is so varied, having a handheld that you are comfortable using makes things much easier.
Currently, my aircraft is equipped with an IFR certified, panel mount GPS, electric back up AI, and a Garmin 396 handheld mounted at glareshield height. That gives me as much or more redundancy as in a current production aircraft. The 430 is used as the primary nav with the handheld providing back up info and datalink weather.
I expect you are considering datalink weather along with your GPS, since that is a primary capabilty of the Anywhere Map system. I can tell you that XM weather is the greatest advance in aviation safety since the advent of the GPS. Even with the inherent latency of the weather info, you can make strategic decsions early enough to avoid flying into anything you'd rather avoid. I've only had the XM weather a short time and it's already allowed me to complete two flights that I probably would not have been able to complete otherwise.
My advice is to go with a purpose built unit like the 396 or their latest version with the faster update rate and larger data storage capability. The Anywhere map system requires more "computer geek" skills to get working initially and is prone to lock up and need rebooting while in use. Especially if you try to run other programs on the unit. From what I am told by my former AC partners who purchased Anywhere Map/Weather, the Bluetooth version is not ready for prime time, which leaves you with the wiring headache of all the components of the AW system. A 396 is a single box with intuitve controls. It can easily go from air, to land, to marine use. It is also an XM radio receiver if you pay for the extra subsription and have the ability to pipe the output through your audio panel.
I personally would not by Lowrance (aviation products)again. They all but pulled out of the aviation market shortly after I bought the Airmap 100. Support was slim to none. They seem to have recently decided to reverse direction again to enter the market, but I wouldn't trust their commitment.
