I've seen a few lists floating around. Is there a general consensus of the best overall build? I plan on taking it to my first store championship so any help would be great!

What do you fly the most?

There is no "best" Dash/Miranda. There are lots of things you can tweak, and performance of the list will depend mostly on the player. Keep in mind your own playstyle and the kinds of lists you expect to face.

There are two basic approaches to Dash, depending on your style. If you tend to play aggressive, then I recommend a Push the Limit build. If you like to take it slow, then a Lone Wolf build will probably be more your speed. Dash's EPT will consequently determine which crew and modifications to equip. (Kanan is gold on PtL Dash, while Rey is better on LW Dash.)

Miranda is a ship you should adapt based on what you expect from opponents. Pick secondary weapons and bombs that counteract your most likely opposition.