Reliable terrain modeller today?

Afternoon folks,

I'm trying to find out which of the terrain modeller currently (as of Feb 2010) are in a usable state - mainly because I wish to model some terrain.

My fall back plan would be to use Blender3D to create it, and import the terrain as one very large TriMesh, which I do not believe is a good way to achieve the goal (performance wise).

Is there a list of the various terrain modelling projects and their current state, by chance? - I've looked and not found it …but experience tells me that's not to say it is not there!  :oops:

So, if anyone has a recommendation, then I'm listening  :smiley: