I've tried both SeaClear and OpenCPN and I agree that OpenCPN is better, at least to me.

I got used to Maptech's chart navigator (lite) and now I use Offshore Navigator. I like the interface the best of all three, but I'd probably be able to get used to OpenCPN pretty easily. Offshore Navigator goes for about $100 and comes bundled with US charts (which are also available for free download in BSB format, courtesy Uncle Sam).

One of the other things I like about Offshore Navigator is it has an "on the water" mode where the standard windows menus disappear and are replace by large font blocks of information (which are configurable). This is good if your notebook has a small screen or you are using a small screen repeater like one of these:

http://www.short-circuit.com/product/VM90.html

No affiliation with either company etc...