It's about personal preferences. Aerobars are awesome, but a little more spendy and as of this time, there are some limits about what accessories can be attached. Some prefer squarish bars. If so, Thule's your company. They come in 50, 55, 65 and 78 inches.
If you like slippery quiet, Aerobars come in 43, 53 and 60 inches.