I have not used
www/iridium, but it seems it is not updated
very often.
I think Chromium is safer (because is updated frequently), but it screws user privacy by default. I was filtering packets from Chromium (executed as another user and in other rdomain) against pf's table with set of Google's IP to prevent phoning home and have applied other measures, but something changed in OpenBSD and config has broken. I am going to fix it in future, but for now I am using Firefox.