Hayek ideology and Thatcher sounds more interesting than capitalism or Adam Smith essay. The last look like some common topics every students owuld think of and those are pretty easy to write unless you come up with some interesting thesis statement. Besides, there's one disadvantage of writing on a general topic - you'd want to include as many things as possible and as a result your paper will become a mess! Just look at this Abraham Lincoln essay - from the first sight it looks like ok but when you start reading, you'll understand it's more of a bioraphy than of an essay. But if your topic is narrowed down, you'll have more space to write about what actualy matters. You won't have the need to write about everything, you'll just stick to your topic and thesis statement. So, I hope you chose the one on Thacher.