In general, it depends on your setup which of those tasks uploads the protected app. Typically, the release build is the protected one, so the tasks you want to use is uploadToAppSweepRelease.
There was a bug in the AppSweep Gradle Plugin 1.5.0 though, which prevented the correct upload. This is fixed in version 1.5.1. If you include our plugin with version "latest.release", the fixed version will be picked up the next time you build your project.
One important note:
To make the AppSweep Gradle Plugin pick up the protected build, it needs to run after the DexGuard plugin. This can simply be done by applying the plugin after the Dexguard one: