My favourite so far is Level 38: Tough Decisions. I like the solution, but I also liked the dumbness it brought out in me along the way.

When there's no limit to tries, and iteration is quick, it seems I revert to "I'll just quickly try this dumb approach, and if that doesn't work then I'll use my brain...". Was that only me?

I've tried to be a bit vague in my example thought process below, to not ruin it for anyone who hasn't tried this particular captcha yet. It's probably (even more) unrelatable if you haven't tried this one yet.

"Perhaps I chose the wrong option at the beginning - I'll try the other..."

And then, even worse: "Maybe I need to back into the parking spot - that's dumb, but I'll try it first and then think afterwards. Oh, it's easiest to back into the spot if I go around the centre bush, but that means basically choosing both options. Anyway, I'll quickly try that first..."