Over the years, I've found that downloading Xcode from the Mac App Store has several disadvantages. You no longer have control over which version of Xcode you are running. And a new version of Xcode gets downloaded halfway and you are unable to continue working.
Most developers also download the latest beta version of Xcode from Apple's website for testing their apps against newer versions of iOS or to take advantage of APIs in soon-to-be released versions of iOS.
There's a Downloads for Apple Developers website where you can download other versions of Xcode, including the latest production version. Downloading Xcode from here instead of the Mac App Store lets you run different versions of Xcode in parallel easily.