I found a interesting website, that is the most complete comparison between available grammar checkers, most of them professional grade.
It evaluates each product by category. This is helpful to remind any language maintainer, of possible areas of improvement. The critic of each of those software pieces, also indicates specific flaws of each implementation.
The page belongs to a software house, so their reviews and criticisms, should be taken with a grain of salt. Regardless of this, the insights are very useful, at least to me.