Which show had better guest stars?
We've seen the old and haggard guest star lineup from The Love Boat.
But Supernatural goes unrecognized for the sheer volume of STAR POWER that have appeared on that show, over the course of 15 seasons.
This is probably not the complete list, but from the episodes of Supernatural that I've actually seen, these are the famous people who have been on the show:
Season 1 Cory Sarah Shahi, Steve Railsback (Texas Chainsaw Massacre), Cory Monteith (Glee), Alden Ehrenreich (Solo), Loretta Devine, Nicholas D'Agosto (Election), Nicki Aycox (Jeepers Creepers 2), Sterling K. Brown, Summer Glau, Linda Blair (Exorcist), Jason Gedrick, Tricia Helfer, Gary Cole, Aldis Hodge, Lauren Cohan (Maggie, Walking Dead), Michael Massee (Crow), Peter Deluise, Helen Slater, Dylan Minnette, Barry Bostwick, Jim Parrack (True Blood), Jack Plotnick, Jake Abel, Mark Pellegrino, Christian Campbell (Trick), Rachel Miner, Paris Hilton, Snookie from Jersey Shore, Julian Richings, Eric Johnson (Smallville), Mitch Pileggi, Corin Nemec, David Paetkau, James Patrick Stuart, Osric Chau, Felicia Day, Curtis Armstrong (Revenge of the Nerds), Hal Linden (Barney Miller), Adam Harrington, Kathryn Newton (Ant Man and the Wasp), Steven Williams (21 Jump Street), "The Miz" (Wrestler), Colin Ford, Finn Wolfhard (It), Alicia Witt, Kurt Fuller, and Adam Beach (Law & Order SVU).
Just to name a few.
Some of these people were in major feature films like Loretta Devine, Alden Ehrenreich (Solo), Dylan Minnette (Don't Breathe), Finn Wolfhard (It), Kathryn Newton (Ant Man), and Sterling K. Brown (Black Panther).
I think that Supernatural beats The Love Boat.