I'd choose to be a Truthwatcher. Being able to see the future has so much practical applications in our modern day world. I mean, I'd be able to see future stock prices, make a hell lot of money from gambling and lotteries and from politicians who want to know whether or not they will win elections. In addition to this already godlike ability, I'd have the surges of Illumination and Progression to do fun stuff with.
Oh! I just realized something! Will I, as a Truthwatcher, be able to read all of Brandon Sanderson's future books right now? It should be possible, right?