First I want to congratulate the people behind XenForo project on their excellent work. Clearly a superior state-of-the-art software and wish you all the best.
My question is; is there an essential "must buy" add-ons (or mod) that I might need to buy?
Something like "bot/spam" blocker add-on which costs $xx?
I mean something that you can arguably say you HAVE to have or your life will be hell; and it costs extra fees.