Take a topic you are interested in, and then find a relevant/controversial issue around it. If you're into sport, talk about the doping scandal, for example should Russia be allowed to compete? If you're into animals, then vegetarianism (as suggested) is a good idea, or perhaps is it ok to keep animals as pets?
The key to a good assessment is to present some facts and viewpoints, but summarise with your own viewpoint. We were allowed to use a powerpoint behind if we felt more comfortable using one, and if you do, be careful to keep the powerpoint to a bare minimum- just speaking from the powerpoint won't even get you a pass. Take it steady, and remember you are allowed to use 'erm' (or similar) to no penalty- they are a part of normal speech.
I got a distinction on mine, talking about the war in Yemen. I used a short powerpoint with just a few charts and key facts, but explained the facts with extra info in my speech. If you're still stuck for topics, the more popular ones in my class were euthanasia, the death penalty, should the police be armed, right to vote at 16 and the state of the NHS. All are topical issues and can attract the best marks.