If you in tight budged, then there are two free renderer that I would look on; Kerkythea and LuxRender. Kerkythea has a commercial sister Twilight (same engine, but streamlined UI. Limited to 32-bit memory space and SU polygon handling capabilities). LuxRender has a fairly new exporter so may need some maturity, but worth look on (sorry no deeper experience with it).
In landscaping one may often need displacement or instanced high poly threes or other entourage. Thea Render can do both, with near unlimited resolution (up to available ram, with Thea 64bit), in reasonable cost. Vue Infinite may be hard to beat with it's EcoSystem, but it may be out of budget.
There are quite many topics on rendering programs, many has a favorite one, but best to test those that look interesting. Also, different tasks may give a need to have multiple renderers available.