Best Aggressive Opening to play with Black

whats your rating...?the purpose of any opening is to gain advantage more precisely if u playing white..if u are playing black your purpose is to neutralise whites initiative and outplay your opponent in the middle...keeping that in mind i suggest u look at guacco piano(which is a repertoire for white in open games that also gives extremely good defence advice for black).....i play it almost all the time against whites e4...u can also go for French defence which is really like multi purpose for any e4 challenges (which is a real black repertoire )....

"... Two-thirds of this book deals with 'Open Sicilian' positions, in which White plays 2 Nf3 followed by 3 d4. This is by far the most common way for White to meet the Sicilian. White opens more lines for his pieces and attempts to exploit the fact that he will be ahead in development.
Let's take a look at the possible opening moves 1 e4 c5 2 Nf3 d6 3 d4 cxd4 4 Nxd4 ... . White is up in development and can move his pieces more freely. Black, however, has a structural advantage of an extra central pawn, which gives him long-term chances of taking control of the centre. A typical imbalance has arisen. The onus is on White to exploit his lead in development in order to secure an early initiative. If White plays passively or his initiative runs out of steam, then typically it's Black, with the better pawn structure, who enjoys the long-term chances. Thus it's quite rare for a state of 'dull equality' to arise. Often in the Sicilian, if Black 'equalizes', he is already slightly better! This structural advantage is seen in most Open Sicilian lines: for example, the Dragon, the Najdorf, the Scheveningen and the Classical Variations. The major exception to this rule is the Sveshnikov Variation, in which Black accepts pawn weaknesses in return for activity. ..." - GM John Emms (2009) in Starting Out: The Sicilian, 2nd Edition
https://web.archive.org/web/20140627122350/http://www.chesscafe.com/text/hansen123.pdf
However, IM John Watson wrote (2010), "... For players with very limited experience, ... the Sicilian Defence ... normally leaves you with little room to manoeuvre and is best left until your positional skills develop. ... I'm still not excited about my students playing the Sicilian Defence at [the stage where they have a moderate level of experience and some opening competence], because it almost always means playing with less space and development, and in some cases with exotic and not particularly instructive pawn-structures. ... if you're taking the Sicilian up at [say, 1700 Elo and above], you should put in a lot of serious study time, as well as commit to playing it for a few years. ..."
First Steps: 1 e4 e5 covers the sort of thing that is, I think, most commonly suggested for players with limited experience.
https://www.newinchess.com/media/wysiwyg/product_pdf/7790.pdf
It might be a good idea to consider Discovering Chess Openings by GM John Emms (2006).
https://web.archive.org/web/20140627114655/http://www.chesscafe.com/text/hansen91.pdf