Forum OpenACS Q&A: Response to Functionality Summary of OpenACS + Comparison to ACS Versions

The reason I'd choose OpenACS, besides all the reasons Don
mentions above, is its vibrant community. If you check out the
ACS forums, you'll only see a couple posts a week. They're
lonely over there... 😟

That could change at some point in the future, but are you going
to bet everything on that?

I think Tcl is fine for development, too. You can learn it in a
couple hours.