I ca't give you a general opinion, just mine:
Your choice is really between Artlantis and LightWorks. But you exploit both for different management reasons.
One reason for getting good in Lightworks is because the application is directly linked to Archicad. Quick, small, well-illuminated progress renderings can help the design process better than by transferring a file to Artlantis. (Others may differ on this.)
Since your firm already has Artlantis, moving to the modern Artlantis is a good move, considering that you have insight into the application and the new release is much better than the old.
Artlantis renders quickly and ultimately makes a better image. This speeds the learning curve. It compares favorably against the LightWorks engine unless you need sophisticated material definitions that few architects do.
I think that time invested in Artlantis will get you better renderings, but that neither application can justify itself at architect's billing rates, so find a promising junior to do the work. This leads to a management issue for the firm.
If the firm is to have an imaging specialist, this person should be focused on a truly hi-end application like Cinema 4D that is capable of network rendering of fly-throughs, has fast rendering, fantastic material and luminous light qualities. This person might not be an architect - perhaps an illustrator/graphic artist who is trained already. Then you can be making superior images that can be a value-added product for the firm.
Dwight Atkinson