All keyword tools suggesting to check manualy to be sure.
I think the best keywords have not competition in adwords or have low competition there. So after you use your favorite keyword competition finder tool, also check adwords competition - if it is high the keyword is not easy and have a lot of adds on the top (4 adds on the top = position5 of rank #1 organic).
If it have low comptition in both, than check the top 20 pages and not top 10 like all recommending! Becasue in positions 10 - 20 may have very high authority sites with bad on-page.
On-page SEO scores sucks. No tool for SEO score checking LSI (like synonyms) yet so it is never accurate. Yes, have a lot of tools that are splitting the keyword on words and checking manual, but this is still semi LSI check. So giving such dump data to keyword difficult score in 2017/18 is a shame.