NeuronWriter is a great alternative to Surfer and only continues to get better.
For the cost of 1 month of a Surfer subscription, you can get a lifetime NeuronWriter subscription!

I use it to write blog posts and to optimize keywords for SEO. I've also noticed some SERP improvements right away.

I just discovered that there is also a Chrome extension, 'CONTADU NeuronWriter - SEO/NLP optimization', so you can integrate the NLP optimization recommendations directly with Google Docs. It also works with WordPress too.

This has helped speed up my workflow significantly. Rather than writing in Google Docs and then pasting content into NeuronWriter to optimize, I can now do it while writing.

This is just as good as Surfer, and the content competition score for keywords now seems more accurate and in line with SEMRush.

It takes a little while to become familiar with the interface, but there are now great onboarding instructions. I've been using it for a few months now, and everything is super intuitive after the initial learning curve.

I have 2 codes for the Silver plan and am very happy with my purchase. If you're looking for a Surfer alternative and to eliminate another subscription, then you've found it!