Which part of the grand canyon is the prettiest (north, south, or west)?

I will be going to Las Vegas at the end of April and am so confused about all the tours to the grand cayon. I'd love one of the tours to be via plane/helicopter so I can see the Hoover Dam and canyon from above, but not sure which part is best to go. There are a bunch of tours to the West Rim, but is it worth it just to go on the Skywalk? I can always drive to the west rim since it's the closest to Vegas, but unsure about whether to go to South Rim or North Rim. I only have time for one. Wouldn't want to drive to South/North Rim b/c it's much farther and don't want to be caught driving at night on those unmarked paved roads. Please help!