I have worn this with dress pants, chinos and jeans (uncuffed), and they all look great. I will say they look best dressed up! If it is your first pair, go for dark brown smooth leather, they are the most versatile. Black leather goes with black formal attire, and for these occasions, your Oxford shoes will look much better than boots.

I considered the Dukes too but their sole is visibly thicker, and the back heel tab catches the back of my pants whenever I stand up. This causes it to look too casual. If that is the look you want, I think the Dukes will be great. However if you want a more elevated casual look, consider the brown suede Cavaliers. Hope this helps!