Dropping from English Advanced to English Standard requires making an informed decision, for which you should consider the following factors:
Different prescribed texts:
One of the most obvious differences between English Advanced and English Standard is the prescribed texts. The main consideration here is whether you are aware of the prescribed texts for English Standard at your school and, if so, whether you have had a look at them and familiarised yourself with those texts to a certain extent. The same applies to the modules in English Standard, which are likely to cover different themes/ideas/issues than those in English Advanced.
If you are aware of the above, do you feel you are confident that you will not face problems with learning and applying the knowledge that you gain throughout year 12 to your assessment tasks/exams?
Alignment:
English Advanced has superior alignment compared to English Standard. Although this should not be the primary consideration (as a student can perform well in any subject, irrespective of alignment/scaling), it is definitely worth noting.
Band 6:
Consistent with the above-established superiority of English Advanced regarding alignment is the number of students who achieve a band 6 in English Advanced compared to the number of students who achieve a band 6 in English Standard. The rate of the former is usually significantly higher than that of the latter. For example, in 2020, approximately 14% of students taking English Advanced achieved a band 6 as their HSC mark whereas a significantly lower 1% of students taking English Standard achieved a band 6 as their HSC mark.
Your performance potential:
This is the factor that is the most relevant to you and which should receive the highest level of attention. Did you feel that your assessment task was too difficult, which led to unfavourable performance and hence your current rank? Or did you perhaps feel that you did not take this assessment task seriously enough (i.e. you did not do your best) and this led to unfavourable performance and your current rank?
Depending on the weighting of your assessment task, unfavourable performance may not be very significant and you may have a good chance of recovering, provided you do your utmost to ensure optimal performance in your upcoming assessment tasks/exams. Your current rank may also indicate because while you are ranked 15/30, considerable improvement could be within reach.
I hope this helps!