Vectorworks (originally named MiniCAD), has been available for some time and was one of the original Apple Mac based CAD programs. It has grown to become a capable product with a substantial set of commands. The learning curve for this software can be quite steep and the interface has a myriad of dialogue boxes and menu items that can be challenging to navigate, especially at first.
For landscape design you would need both the core Vectorworks plus the plugin, Landmark. Landmark is a set of landscape tools designed to assist in selecting plants, to do labeling and scheduling etc. Vectorworks was a popular choice among landscape architects for some time as no other professional CAD for landscapers was available for Apple users and if you’re already a Vectorworks devotee then adding Landmark to the mix would be the easiest choice with very little learning required to comprehend the landscape tools.
We definitely get a mixed result when talking to users of Vectorworks about its ease and speed with opinion being divided down the middle on the subject.
With LANDWorksCAD now firmly in the market Vectorworks has some competition that will hopefully drive some improvements.