The Argon 18 is the better of the two though as others mentioned the crank could be problematic especially for a new rider on a short track. Kissena in Queens is a 500m track so 175 would be reasonably safe with it's shallow banks. Trexler is I think 300m and is noticably steeper. CA has 250m tracks which are the standard and have the steepest banks but until you get comfortable leaning through the banking and keeping your speed up then the longer cranks have a high chance of hitting the track and crashing you. 144 bcd cranks are traditional but you'll be fine with 130bcd. Miche makes a nice, affordable option. Sram Omnium is popular but recently discontinued and harder to find. Plus side is the DA crank on the Argon should be easy to flip.