I believe an informed decision would require you to consider a number of factors. Business Studies is not considered to be a high scaling subject and (I believe) neither is Engineering Studies. With that said, scaling of a subject should not be prioritised with respect to subject selection and ATAR aim. Keep in mind that you can achieve a high ATAR with any combination of subjects, meaning that your focus must be on your performance across your subjects going forward. Another important thing to consider is that the higher the marks you achieve, the less significant the effect of scaling becomes.
Favourable performance in HSC Business Studies relies heavily on your knowledge of the syllabus, your ability to effectively manipulate the content in addition to knowledge and effective incorporation of case study material. If you believe you would be able to ensure those aspects are consistently maintained throughout year 12, there is a high chance that you will end up performing well in Business Studies. While I am not sure what the Engineering Studies HSC course entails, I believe it would generally be considered to be a more difficult subject.
Taking a subject you like instead of a subject you don't like should normally be the priority. Considering the fact that you like Engineering Studies more than Business Studies, you may wish to drop Business Studies. However, this should only be done if you are confident in your ability to achieve favourable results in HSC Engineering Studies, which will require you to be regularly studying and staying up to date with content, allowing you to perform well in your assessment tasks/exams. If you believe that despite the fact that you prefer Engineering Studies, you believe you would be able to ensure superior performance in Business Studies, the subject to drop would be Engineering Studies, because in such a case performance is an important consideration which ultimately impacts your ATAR.
I hope this helps!
