My AppData/Local is 14GB, mostly caches from Chrome, Firefox and Spotify. My AppData/Roaming is 3.3GB, mostly my emails (with my Browser's localstorage a distant second).
Chrome's cache is in AppData/Local/Google/Chrome/User Data and Firefox's cache is in AppData/Local/Mozilla/Firefox/Profiles/. The only big offender on my system is npm with a cache in AppData/Roaming/npm-cache
Thunderbird infamously places the local copy of IMAP mails (i.e. Effectively a cache) into Appdata\Roaming. It's the single largest directory I have there. Everything else is quite reasonable in size.
Chrome's cache is in AppData/Local/Google/Chrome/User Data and Firefox's cache is in AppData/Local/Mozilla/Firefox/Profiles/. The only big offender on my system is npm with a cache in AppData/Roaming/npm-cache