Asking what the best exchange traded funds (ETFs) are is the wrong way to approach the subject. There is no single ETF that suits everyone for all situations. Although there are investment managers that offer portfolio building services by using ETFs. But what would be the point in paying someone to go out and buy ETFs when you could do it yourself?
The only thing I try to watch out for is to make sure the ETFs are coming from a well-established provider. The top providers quite handily provide a broad selection of ETFs so I feel better about sticking with them.