How can I compare the contribution of two predictors in two different sorts for machine learning algorithms?
No you can not.
You are forgeting about variable interactions (C-A,D-A,E-A, etc...)  that could favor A.

You could answer following qestion: If I were to measure information in my variables via variability how would I proceede? For example PCA

The more information you have in the variable(predictor) the higher the chance that it will contribute more to accuracy