Permanent fix for Safari downloading download files instead of the actual file

I've seen many people describing this same issue with Safari downloading .download files instead of the file itself. Thankfully, one of the workarounds (right-clicking the .download file and select "Show Package Content" reveals the intended download file). However, I don't want to do this extra step after every download! Is there a permanent fix for this? I'd prefer to use Safari - but I may have to switch to Chrome.

[Re-Titled by Moderator]

Original Title: Safari .download file issue