Surfer SEO vs. Frase vs. NeuronWriter: Which gives the best ROI?

I need a content optimization tool to improve my on-page SEO. Surfer is very popular but quite pricey for me right now. Have you guys found better or similar value in Frase or NeuronWriter? Looking for honest opinions before I subscribe.

The best option depends on how much content you publish. If you only need basic onpage optimization, a cheaper tool like NeuronWriter may be enough.