What is the most successful ETF?

Can you elaborate on the most successful ETF currently available in the market? Are we talking about an ETF that has consistently outperformed its benchmarks, or one that has seen significant growth in assets under management? Additionally, are there any specific factors that have contributed to its success, such as a well-diversified portfolio, low fees, or a strong track record of returns? Understanding these details will help us identify the most successful ETF and assess its potential for future success.