You're sort of putting the horse before the cart. You are correct in stating that handle kits are in NO WAY interchangeable between brands, and actually in some cases not WITHIN a brand. SO. You should go to a plumbing store that has some displays and catalogs. Pick out the style of faucet you want. The catalog will show what in-the-wall rough in valve you need to use. If you want to specify a certain valve function, like pressure bal or therm. controlled, then choose the valve and the catalog will show you what trims will go with it.
Most of us here would recommend something other than Kohler, for various reasons. Delta and Moen come to mind.
The final will be whatever the lady of the house wants!