This is a fun topic.
Well, I love everything Boba keeps in his personal arsenal. His is a varied, eclectic collection of weaponry which, when matched with the skills of an expert like Fett, have become the stuff of legend. For a man with so much at his disposal, it's honestly a little hard to try and narrow it down.
But if I could choose only one single piece, it would likely be Boba's EE-3 carbine. An obvious choice, maybe, but one which is pure Star Wars!