There's a lot of variability in rim brakes. For dry road riding, I haven't found discs to offer any tangible braking advantage over my best rim brakes.
If the rim braking is a bit spongey, make sure that you're using good compressionless housing, and that you're avoiding excessively tight bends in the routing. And if the pads are inappropriate for the rims and/or conditions, you can end up losing some braking force or experiencing grabby modulation.
Good rim brakes that are set up well can usually achieve power and modulation very close to what hydro discs can provide, at least until we start dealing with rain. Disc brakes tend to cut through water on the rotor better, less hesitation on the initial brake engagement.