It’s such a crapshoot you can never tell, and if there’s an accident things can change for the worse pretty quickly. I’ve had both good and bad luck with 15-210-5. Both the 15 and 210 can get all snotted up, but I don’t think either of those freeways drop down to as few lanes at the 5 does in stretches.

I agree that starting your drive late at night will increase your odds. If you decide to take the 5 and OC is a mess, taking the 73 over to the 405 and using the carpool lane will help a lot. It seems that when the 405 gets choked, it happens in a cluster (like around LAX and UCLA). When I5 gets choked, it seems to go on forever.

Using Google maps and/or a Garmin with realtime traffic can help, but sometimes there aren’t any viable alternate routes.