"Although Winston Smith attempts to secretly rebel against the norms of society, he and Julia can not possibly ever truly beat Big Brother."
With that thesis statement you have the opportunity to completely discuss just about any attempt Winston makes to express his individuality. And because of the subordinating conjunction at the beginning, you are also obligated to inform your reader of the futility of Winston's efforts against Big Brother. This type of thesis statement is a strong thesis statement because it allows you to present to your reader counter arguments and then refute them.
"Winston Smith shows the importance of individualism through his journal/diary, sexual promiscuity with Julia, and questioning of Big Brother's authoritarian regime."
This thesis statement is more direct in what you would write about. You make a point, and then alert your reader to the fact that you will provide evidence in three specific areas.