In a new (6-27 August 2019) survey of 1,584 SEO professionals by Rand Fishkin's software startup SparkToro, 66.3% of respondents said that in Google's ranking algorithm, the weight given to various ranking factors varies widely depending on the query.

That makes it tough to generalize as to the most important Google ranking factors in 2019.

But keeping that fact in mind, here's what the survey found to be the top 10 Google ranking factors in 2019, scored on a scale of 0 to 10:

1. Relevance of overall page content 8.52
2. Quality of linking sites and pages 7.87
3. Use of query-relevant words and phrases 7.50
4. Domain's perceived expertise, authority and trust 7.48
5. Mobile friendliness 7.26
6. Exact match keyword use 7.12
7. Quantity and diversity of linking websites 7.04
8. Content's accuracy withy accepted facts 6.97
9. Link authority of host domain 6.9
10. Page's perceived expertise, authority and trust 6.87

SparkToro notes that scores of those 10 factors by those 129 respondents who said they are in the "top 10% of the SEO field" were consistent with the scores assigned by the overall population of respondents.

Ranking factors on which respondents most disagreed as to importance were (top 5):

1. Keyword in the domain name
2. Use of Google AMP
3. Age of the website
4. Keyword used in the URL
5. Content's accuracy with accepted facts (the only factor also on the top-10 list)

Respondents were also asked to rate on a scale of 0 to 4 each of a list of trends on their impact on SEO in the next 3 years. Here are the top 4 rated most impactful:

1. Google entering verticals/competing directly vs. publishers 3.36
2. Advancements in machine learning/artificial intelligence 3.24
3. Zero-click searches on Google 3.10
4. Changes to quantity/presentation of Google Search Ads 2.99

Fishkin added this afternote to the survey report:

"One of the biggest misses of the survey this year was my failure to ask where the respondents did the majority of their SEO work. It’s my perception that the importance of various ranking inputs has great variance depending on query language and geography, and I hope to show that in future years."

That's an excellent point and one to keep in mind, especially when trying to optimize websites for international markets.