Should a node follow the longest chain, or the chain with most work while syncing?

I’m reading mixed things online – some saying to follow the longest chain, and some say to follow the chain with the most work. But I’m not convinced of the former.

If the node follows the longest chain, what is to stop the scenario of a bad actor sending a completely false chain to my node with a really easy target of 1? The chain could be longer than the main chain, and I can’t see any consensus mechanisms preventing that chain from technically being invalid.

If following the chain with the most work is the way to go, then how can we verify most work? Is it just a case of following the chain with the lowest integer value for its hash (as my understanding is that the hash needs to be below an ever-increasing target, and shrinks in size as more miners join the chain)?

Any guidance would be much appreciated.

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