Garmin everything...In the vehicles we have Nuvi 750's which I bought on sale from Amazon the beginning of this year.
Handheld: A variety of Garmin E-trex and newer.
Boat: Garmin Again
Airplane: Integrated Garmin avionics, Garmin handhelds.
USB for use with laptop? Garmin.
I have the first GPS I ever purchased, a Trimble handheld that cost me in excess of $2K in 1990. I used it in Desert Storm. It still works, but it's big, heavy, and slow. The $90 yellow E-trex I bought almost 10 years ago is head and shoulders better than the Trimble, and the newer ones better still.