Interesting thread. I view it as the “worst add-on i own”, just a disclaimer. Through that lens I gotta say it’s the Aerosoft CRJ. It’s not terrible but I usually don’t buy add-ons until I’ve seen reviews etc. Probably saved me a lot of money. Also means I only a have a few but very good add-ons.
The reason it’s the CRJ is that it’s been out for a while and there are still quite a lot of things that are buggy or just not correctly implemented. There hasn’t been any updates in many months and even the looming update doesn’t seem to fix a lot of the bigger issues (at least for me).