I have used Airnav pro
for iPad when flying , although the app is a reasonable price the charts are extra, and can seem expensive. Do not rely on the iPad 3G for position fixes.
I use the bluetooth gps GNS 5850 which has been very reliable coupled with Air Nav Pro.
For planning Skydemon (app + pc) is superb , I ran the trial "go flying" version last week when I was in the back seat to see its capabilities and was impressed. Airspace/terrain/offcourse warnings were nice + clear (something not on Airnav Pro).
My android phone favourite is "AirReport" - nice to see at a glance all the metars in area.