The hunt for a reliable is a rite of passage for preservationists and emulation enthusiasts. Archive.org remains the best resource for this due to its legal goodwill, fast download speeds, and file integrity.
Instead of general terms, try these:
There is no law that says you can download a ROM if you delete it within 24 hours. That is internet folklore.
: Files are generally community-vetted and free from the aggressive ads found on private "ROM sites."