If you could select quality stocks that will survive for long, you should go for focused approach. You have mentioned some quality stocks, are you sure they will survive long term? Do read their balance sheets. When you are focused its not bad but do need to be thorough of your choice. Is it actually quaity? That depends on you.
However if you unable to work through the process and not sure of, better to diversify. It will reduce your returns but also safeguard your portfolio.