As Brian said, Garmin is by far the most popular. There a quite a few different options within their line of track and train systems and some might fit you better than others.
For simplicity the Pro550Plus is hard to beat but if you need or want topo maps on your handheld then you would want an Alpha 200 or 300.
If you want the ability to use Inreach to communicate when out of cell signal then the "i" variations of the 200 or 300.