I've used Delorme Topo, but don't have a GPS. It's good in some ways, inaccurate in others.
The plus is that it's reasonably robust, easy to make and save new routes, has lots of detail, has a fair amount of rail information, and you can even get some info like campsite locations.
The main gripe I've heard is that the elevations are (allegedly) off. Printed maps are OK, but could be better.