I'm a big fan of high, middle, and lower level lighting...
If you have a Lightbar... push a dash light on the dash...
Slick top... definitely up under the RVM... n if u have the funds. Why not stick one on the dash for that middle level lighting.
Also varies with what type of vehicle u have.
Your goal is to hit most drivers in the RVM. So depending on how high ur vehicle sits should also be a factor.
Why don't you tell us some more about your install and we can make recommendations. Pictures help too.
At the end of the day lighting positioning is a case by case basis for most upfitters based on budget, type of vehicle, use and personal preference.
Seth