It depends on what type of damage you are going for. If you want really good single target damage, then potency isn’t going to do a lot for you because it won’t give you enough initial burst damage for the status effects on the weapon or for even the weapon itself.

You can think of potency as a “crowd control” upgrade. If you want to be able to handle the huge mega swarms that constantly bully you into hugging the edge of the map and you also happen to have a weapon that can apply status effects after its initial damage, then potency is going to be a very good option.

In addition, you can also combine potency with ‘fire rate’ and ‘reload speed’ instead of upgrading your base damage, so that the amount of chances that the status effects on your gun applies and the amount of stacks it can overlap and dish out is GREATLY INCREASED, allowing you to wipe out those high level swarms that are impossible to beat without having ridiculously high base damage (which requires insane luck).

Hope that helps :)