All the maps on GPSFileDepot are for Garmin GPSes. The exact model of GPS has a lot to do with personal preference. Several Garmin handheld models will do what you have listed in your wish list.
First you need to decide if you want one with a touch screen or buttons. Each have their advantages. Touch screens are generally easier for a complete newbie to GPSes to learn, are faster inputting data such as comments, coordinates, renaming Tracks, waypoints, etc. The biggest downside of the touchscreen is that the screen is not as easy to read, (this only applies when outside on a bright sunlit day when the unit is in the shade), as the non-touchscreen models are. This aspect of the touchscreens has been improved with newer models. For my ATV I prefer the touchscreen and probably won't ever go back to a button unit because I enter a lot of tracks, waypoints, comments, etc. for map making while I'm out riding.
Since your first request was for it not to cost a fortune and to be able to do everything else you want, I would recommend the Oregon 450 (a touchscreen) @ ~$250 or the 62CSx (buttons) also about $250.
If you want to go up considerably in price then the Montana would be a very good unit, but pricey. The Oregon 600 would also, but at present it seems to have a few software problems that need to addressed, Garmin usually ends up correcting these after a while.
I use the Oregon 450 all the time when riding and don't have any problems changing screens while riding, but it is usually just changing the zoom level or to view the dashboard view. The Etrex units would fit your wish list but the screens are very small for using on a 4-wheeler while moving.