We use Garmin at work. The real deal Geographic Positioning Systems for geo-referenced mapping and off-grid wayfinding.
Never had an issue.
We've also run Garmin's consumer grade handhelds when skill and accuracy aren't necessary, and have seen greater than 10' accuracy with averaging.
FWIW, Humminbird has been quite good for us, too, but its PC user interface really sucks. Apart from marine systems, I don't know what they offer in consumer goods.