My experience is that 0-based offsets (and use of < or even != for upper bounds) mean that I should almost never have to write something like idx - 1 or idx + 1.

I came to 0-based offsets later in my career, having started with Matlab. So I have some real experience with 1-based offsets. Experience that was 'untainted' by being used to a different option. I much prefer 0-based.

Especially because I now sort-off have a linter rule in my head 'if I am writing i - 1 then I am making a mistake or doing something the wrong way'. Which has been quite successful.