Today there are a lot of good locks to choose from.
I have 2 locks, when I go bike camping or touring, I carry a fairly lightweight cable, can't recall the thickness of it, I've had it for 40 years, but it was the thickest bike cable at the time, and a Master Lock Magnum M175XDLF combination lock (so I can't lose the key and be screwed).
Now when I go RV camping, or if I'm going to be gone from home for a while, I'll lock two bikes together in the garage to make it difficult to carry two bikes together, so I use a better chain lock called Abus 8KS chain with the same Masterlock combination lock.
There are better locks than what I got, a YouTube video tried to cut that chain, and another video tried to cut that lock, and they were worn out trying to get big bolt cutters to break them, so I guess since the guys on the video couldn't break them they must be half way decent lock and chain.