I don't care either way regarding lettuce. My mrs swears by it to help her sleep. I've tried it a couple of times before beddy bys and it has relaxed me.
From the OP's list, I can't stand tomato, celery or cucumber, and I'm not keen on sweetcorn. Lettuce is essential for me, plus it has the additional value of bulking up a sandwich, to give it a little extra than plain cheese/meat.