Most agressive openings for black?

What openings do you know in which black fights for the advantage, not for boring equality? I want something very aggressive, but not things like Latvian Gambit, which are unsound. Is Sicilian really black's best chance for the win against 1.e4?

Yes, the sicilian defense is blacks best chance to win against 1.e4, statistically. However, at our level (<2000) its best just to stick to the openings that we first learn because a lot of moves are mistakes. If you want to learn an agressive opening for fun then I do reccomend looking at the open sicilian. It is by far my favourite opening especially in the najdorf where white castles queen side. I have had many games where I am at the edge of my seat and eyes glued to the screen because of all the attacking chances from both sides. When you win its all the better from all the tension. Players like Fischer and Kasparov have played beautiful games with the najdorf. 

Good luck if you choose to play the sicilian!!

I don't know why, it's not the strongest, but I fell in love with the Smith-Morra version of the Sicilian......not everyone is familiar with it, I guess, cause I have a lot of fun with it. Comments, please.....remember, I'm in the 100-1200s so not very "booked up" plus I'm 75yrs old.

How about 2300 guys? :) Yes there are different levels, but even 2400 guys have been amateurs in past so they probably know something about things and what would improve skills. Just generally I have seen many people saying in different areas in chess that there isn't much of objectivity and players can practice, play and do what they like. I think chess is quite objective game and the sooner person act based on that the better chances he gets to improve.

Against. 1.e4 Najdorf is objectively the best weapon. It's sharp opening and equalizes right away, although there is some prize black has to pay. Lines are critical and it is more risky for black because he is often less developed and his king is more target than white's. If he doesn't know the theory he may lose quickly. Black can play some lines that titled players have tried but it's better to check from opening book or database what kind of results there have been and also somehow try to understand the ideas.

When I was under 2000 I had difficulties to really understand the ideas behind the moves in Open Sicilian but on that time I didn't have anyone as teacher. I don't know could some teacher have helped me, it's hard to say

But if you play 1.e4 c5 as black you of course have to know how to play against Alapin 2.c3 and Closed Sicilian 2.Nc3.

I think Pirc defence also often fights a lot although it gives some advantage for white. The wing attacks are typical in this opening.

I think there's a difference between objectively "best" and functionally playable, and until you are playing really really strong opponents who know a lot of lines are and likely anyhow to calculate the very best moves, you can find many ideas that are effective.  

Nigel Short pulls out a slick win with a Bronstein-Larsen variant of the Caro-Kann here:   http://www.chessgames.com/perl/chessgame?gid=1628507

Is this black's best opening, objectively?  Probably not.   But it's super dangerous and highly tactical, so a guy might choose to play it if he's that kind of player.    

It's certainly not boring.