Songs are not very highly regarded by HSC markers and they do not often show a depth of language, nor do they provide enough quality for academic analysis in the HSC exam.
Poems are a very underestimated texts; they are studied explicity in Module B 'Close Study' and 'Critical Study' and the complexity of language and technique is substantial.
Have a look at
www.hscdiscovery.com.au for lots of suggestions of related texts (poems, short stories, short films etc)