Who is the best ETF?

As an investor seeking to diversify my portfolio, I'm curious to know - who is considered the best ETF out there? With the vast array of options available, from index funds to sector-specific ETFs, it's difficult to gauge which one truly stands out. Could you please elaborate on what criteria are typically used to evaluate an ETF's performance? Are there any specific funds that have demonstrated exceptional returns and stability over the long term? I'm eager to understand the nuances involved in selecting the right ETF for my investment goals.