What is the best portable gps device to have?

I'm thinking about buying a gps device for my truck. Something portable hopefully. What's the best one to get?|||Absoloute best one, i beleive is TomTom....You can get a decent one for 90-120 dollars though. TomTom one's are around 250 bucks... They are all pretty accurate, but if you're travelling frequently you want more features...go with a 150 dollar system