I long ago decided that if a GPS doesn't say Garmin on it, I'll regret owning it sooner or later. So, I fly with a Garmin Aera 500 at present, and am delighted with it. I had a PDA/GPS/FMS combination which was vastly inferior to any dedicated aviation GPS that I ever used.
Other tools I do use however:
Navbox Proplan
Aviation Tools Free for Android
Great Circle Mapper
And a 1:500,000 retracting tape measure bought online from Aircraft Spruce.
To be honest however, I do still do a lot of my flight planning the old fashioned way with a Plog and whizz-wheel. I find it enjoyable, and going over the chart carefully makes the flight subsequently less likely to hold surprises.
Plus, flying only about 100 hours per year, I don't begrudge a bit of time spent flight planning.
G