Submersables are the only kind that i have so im afraid my opinion might seem a little biased :what:
In my opinion however the submersable type must be the best all rounder as this seems to be what most people have in their tanks
I run all of mine completely submersed but you can leave the top and wire etc out of the water with most types if you prefer.............i however always mount mine as low in the tank as i can as heat rises therefore in my opinion this is a better more efficient way of mounting them