I would be faster. Faster at practicing. Faster at reading. Faster at learning. Though I'm already good at all of those things and faster than most, but not as fast as @ryzeonline (he's an actual genius) so I would choose to be faster. Not to keep up with him but because that's all that's missing for me. But I can manifest anything I want really. If I want to be faster, I would just practice being faster so perhaps I don't really want that. But it was the first thing I thought about to answer your question lol.
What about you @sophiavictoria you didn't say what talent you would choose???
I liked your answer, and on second thought you are absolutely right. Seeing this way I wanted to be a genius.