Need advice regarding ETFs

As a retail investor, I don't have time to analyze stocks individually and would rather invest my money in ETFs only. I'm considering investing in at least 3 or 4. I need advice regarding which ones are the best and if I want to diversify, which ones I should choose. I plan on holding for 7+ years minimum.

Also it is not too common in Pakistan to invest in ETFs, is there any reason behind that or are ETFs just a new phenomenon that people will slowly get used to? Since most retail investors abroad only go for ETFs, especially in the US.