Never get class tutoring for English. It's much too vague and impossible to concentrate on any specific area of study.
The effectiveness of tutoring depends on the individual. Some perform better in a competitive environment - a class, while others prefer to have the teacher focus on only their problems.
Generally, private tutoring is preferred as you buy more time for yourself with the money. However, in some cases it would help to have several other students in the class for the purpose of comparing the depth studied in different schools, and being open to a wider range of problems and discussion topics.