When I was traveling back from Turkey, we stopped in Heathrow, London for a 5 hour layover. There I found Adrian Goldworthy’s biograpy of Julius Caesar, titled simply Caesar.
He writes in a lively, engaged tone instead of the dry, objective tone of a historian. He weighs the contemporary evidence — letters, commentaries, histories — and always keeps emphasizing that Caesar was not inevitably successful in politics or war.
If you have watched HBO’s series Rome, you might find this biography worthwhile.