I use a PDA +
PocketFMS
Pros:
Relatively little cost if you already own a PDA. (Software is free. For €50 you can get more detailed maps.)
Software updates are frequent and free. They listen to their users and implement many of their suggestions.
Database updates are also free.
PC version makes planning very simple and quick, and they transfers all data to the PDA.
Maps are clear, detailed, and customisable (unlike memory map).
Colour display.
Unlike many Garmin units, PocketFMS has VRPs included within its database.
More extensive coverage of airfields than most dedicated units.
Worldwide mapping database, with no restriction on what FIR's are loaded.
Cons:
Not a dedicated aviation unit. It comprises PDA, GPS and Software. More interaction=more possibility for difficulties. (In practise once you get it to work, there isn't usually problems after that.)
Database doesn't come from a big company like Jeppesen, and may (and does) contain some errors. Once you flight plan in conjunction with your paper chart, you should stop any such error.
Screen is not as readable in direct sunlight as many dedicated aviation gpses.
I hope that helps you with your decision!