For several years our company has been moving away from core SEO services and more in the direction of building authority sites and full content marketing strategies.
If you are still primarily doing SEO, you are probably rather upset about the lack of data available from Google now. What used to be a quick report in Google Analytics to see what organic keywords were generating traffic has now become a headache.
There are still several ways to see what is working best. SERP reporting still works so if you pay for a SERP report you will still be able to know your ranking, and if you know traffic on those phrases and your position, you can calculate an estimate of your traffic from the keyword phrase.
Another simpler way is simply to look at which pages are getting organic traffic. You may not know the exact phase that is best, but you will know generally which pages are succeeding at ranking and attracting organic traffic and which ones are not.
However, our advice is to do what Google has always wanted you to do anyway. Focus on building high authority websites with great, regular content and encourage sharing and linking to the article through non-spammy ways to achieve a site that will provide longer term value and be more resilient to changes in the Google Algorithm. You should still have a good keyword target or two in each article and optimize by using it once per 100 words, but do not worry about the actual ranking too much. Your time is better spent moving on and doing another great piece of content.