how is mark antony a good leader?

Antony was a good leader because he was able to use logic and emotion to sway the people. Brutus was very stoic and even though he made a great speech he only appealed to the practical side of the people of Rome, where Antony appealed to the emotional side of the people and also the self interest of the people, bringing up Caesar's will and the money that was promised to the people. He is also a very loyal and dedicated person, as you can see from his soliloquy right before the funeral speeches when he's talking about his revenge and how Caesar will rise with Ate, cry "havoc!" and let loose the hounds of war. And in the very end when Brutus kills himself, he is still very respectful of Brutus and speaks of how Brutus was a true man.

but on the flip side, Antony did have a few bad qualities. For example he wanted to change Caesar's will so the people got a bit less money and Antony personally got more money for himself.