Sounds like you're quite familiar with the product, so if none of the missing 15 features impact you, and rendering - particularly interiors (which are very time consuming to illuminate nicely in AC's version of Lightworks) - is critical to your workflow ... I'd go for START and Artlantis.
http://www.graphisoft.com/products/acse2012/comparison.html
Do note that Artlantis R will ONLY produce still renders. If you need animation or VR, you need the more expensive Artlantis Studio. In contrast, while ArchiCAD's animation tools are quite primitive, you can product animations with whatever rendering engines are available. So, you could do a simple OpenGL animation even with START .. but would need the full license to produce an animation video using sketch or lightworks.
Artlantis had a free trial version, so you might want to watch the videos on Abvent's web site and give the trial a go before deciding for sure?
http://www.artlantis.com/index.php?page=tutorials/index
http://www.artlantis.com/index.php?page=download/demo/index
Cheers,
Karl
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB
One of the forum moderators