Which do you prefer and why? I am trying to up my clothing game and need some knowledge.
Khakis, in modern parlance, are really just chinos (generally refers to khaki-colored ones, of course), so we're really just talking about two different kind of pants.
"Dress pants vs chinos" really just comes down to the level of formality dictated by your social/professional surroundings and the rest of your outfit. Modern business casual workplace? Chinos with a casual button-down. Weekend wear? The same, or just with a tee or sweatshirt. Dressing up for a fun social event? Perhaps chinos, casual button-down, knit tie, unstructured sport jacket.
Traditional business casual? Dress pants, dress shirt. More formal? Dress pants, dress shirt, tie, sport jacket/blazer.
Depends on formality (personally I don't make a distinction between khakis and chinos).