I’ve had the ‘strengths and weaknesses’ one, and I’ve used it too. It’s a pretty common question.
The trick of course is to come up with a weakness which is really a strength, like the ‘perfectionism’ thing. Except, perfectionism is the “I was expecting this question” response, and a bit of a cliché (which is annoying, because it’s fairly true for me – I tend to focus on minutiae rather than the bigger picture).
As an employer, it can be a real eye opener. I once had a candidate enthusiastically tell us that he had problems with his temper, resulting in him punching out his previous boss. 😯