I have the garmin dome unit.

Can't speak for the other brands, but once we you have one, you won't want to run again without it. Nothing like being able to see through the rain, fog, and darkness. While it doesn't mean running WOT, you still have to be cautious, not having it out in those conditions seems like it would be unsafe anymore.

With that being said, get online and review the each one. I like garmin stuff myself. Its simple and it works. Menus are easy, and not confusing. Can't speak for the others, but if you can get your hands on some before buying I would try to make a decision that way. Maybe slide by a west marine store and see if they have any displays you can look at.

Whatever decision you make you won't be disappointed. I wish everyone had one. It is one object that everyone should have and really makes it safer for everyone.