As this thread is linked under the "important" ones I thought I add this:
I have recently had a play with the new Avmap EKP IV, courtesy of Harry Mandelson (
www.gps.co.uk)
Without much doubt this is the
best GPS on the market, for mainly-VFR flying.
The display is amazing. A huge colour moving map, very clear. GPS is mostly about situational awareness and this product will deliver more of that than anything else out there - the screen is twice the size of most popular units.
The map is the same as most other units: the standard Jeppesen GPS map.
It is also near the top of the handheld price range, but this is the sort of purchase which one makes only once in a good number of years.