Sorry for going off topic,
Besides HHN, what SoCal haunt should I go to?
Honestly depends a lot.
If you like a more extreme, interactive haunt, LA is dotted with insane one-off walkthrough attractions. Now, I actually haven't tried any of these, but I know they run the gamut from "slightly longer/more interactive HHN haunt" to "legal psychological torture." I recommend doing a
lot of research before trying one of these; from what I understand though, Blackout, Delusion, and Creep LA are cool haunts that aren't too extreme for people who love HHN. I also hope Blumhouse of Horrors comes back one day; it was one of those slightly-more elaborate HHN mazes that's great for people just starting out.
If you want something a little lighter/on the level of HHN, though, Knotts is honestly alot of fun to do, no matter what people say. Mazes like Dark Ride and Paranormal Inc have alot of fun gags that I haven't seen at HHN yet. I'd say the scares are generally weaker at Knotts, but the mazes are often so imaginative that I don't care and have fun regardless. HHN and Knotts + a small haunt like Delusion is honestly a pretty good rotation. Do be aware, however: Knotts doesn't rotate their mazes at near the level of HHN, often only introducing one or two a year. That partially means that they save money and don't have to make as many black wallz, but it also means that it can occasionally feel samey year-to-year. They do try to add rooms / new twists each year, though, so they have that going for them.
Dark Harbor kinda slipped for me in recent years, but they've had some classic mazes like Deadrise in the past, so I'd at least check them out if you get cheap tickets.
I don't know about WB's event, honestly. Maybe it's the HHN fanboy in me talking, but the IT experience last year was kind of weak. It was free, so I really didn't care, but $80 nights for Warner Brother's thing, if it's on par with last year, is kind of bat-belfry bonkers for the quality we saw last time. The videos I've seen for their haunt really don't bode well. Again, if you get cheap tickets, it shouldn't be an issue; at least the Arkham maze looks pretty neat. Just kinda weak on scares.