San Francisco -- Silicon Valley has the world's top startup ecosystem, according to new rankings compiled by Startup Compass. The top-25 list is based on more than 20 factors, such as startup success rate, availability of capital, market size and founder challenges. The report describes the attributes of Silicon Valley -- which in the study includes San Francisco, Oakland, Palo Alto and San Jose -- as "Biggest throughput. Strong early-stage funding ecosystem. More mentors. Most Ambitious. High Risk." New York, London, Toronto and Tel Aviv round out the top five. The complete rankings are available at the link below.