Gotta go with the Garmin crowd. I've had quite a few, 2 for auto, two golf GPS's, a Garmin Summit for hiking. All have met or exceeded my expectations - I wouldn't have anything but Garmin. I use my current Nuvi 1490 in my truck, in my wife's Edge, I take it when we fly in case the rental isn't equipped with one.
The portability alone is worth it to me, but the option cost of a built in GPS is outrageous, and updating can also be expensive, and can be a hassle with some models (I have a buddy who had the OEM unit in his 2003 Honda, and it was a $1000 plus option, and had to go into the dealer for any updates) . I paid $189 for my current one about 6 years ago. It has served me well in 4 vehicles and is still going strong.