For me it has been the Joyo de Nicaragua Antano and the Tat J21!!!
Every vitola of the JdN Antano has done me in! Even with sugar I get shaky and light headed. The last one I had was the lancero. I thought this doesn't look so scary and then it snuck up on me and punched me in the head!
Back in March, Tony (Beagleone) in Irving Texas gifted me a Tat J21 and then I smoked another a few months later and both times felt like I was drunk after I stood up.
I enjoy the taste of these two wonderful cigars... Yet I have since vowed not to smoke either again!