All things considered equal, it is about personal taste/style. However, all things are never considered equal. All properly designed boards are designed with fin configuration as a component. However the tendency for some is to design for a large spectrum of riders and style, hence multiple fin boxes/options, while some still hold on to the archaic one size fit all or ride like us mantra. Overall a quad fin will be more stable allowing the rider to push harder on their rear foot compared with a twin. Twin fins requirer a lighter foot, and have a tendency to feel 'squirrely', especially with the wide tail of a wake surf. Depending on the board design, both configurations can be equal in speed, but a twin will almost always feel looser which is most often confused with speed.
All quads can be ridden as a twin by removing or not using rear fins; however, a twin fin cannot be ridden as a quad. So, best to buy a quad, fiver, sixer or sevener.
Zach, first try your sixer with all six fins; as you get comfortable, you can change up fin set up to a quad, or a twin, or a twin with canards.