whats the most interesting variation of the sicilian?

No matter what your main line choice is,  white has many options on just the 2nd move- the Smith and Wing gambits, c3, Nc3, f4 (and even odd moves like 2) b3 or 2) Na3 - as analyzed in books such as 'Secrets of Opening Surprises' (the SOS series by 'New in Chess') 

Thus, when playing the Sicilian as black,  as much as you want to play your main line- there will be many times you will face all these 2nd move white options, so that has to be taken into account- if you are wiling to devote the study time to all those sidelines.  Perhaps it might also be good -  if you are an e4 player, you also need to determine how to play against the Sicilian as white - play against your own lines, or adopt a 2nd move sideline?  

I actually am an e4 player and currently play sidelines against the sicilian...rossolimo, moscow, alapin. Also I used to play the closed sicilian as white so getting ready for the sidelines probably wont be a great deal of work of work for me. Im not that familar with the grandprix, wing gambit or the b3 line but I think I prefer to see if I can figure out what to do against those on my own before doing any special study for them.

Silly? I prefer to play solid Sicilians that are flexible. Not Sicilians where to win you have to exchange sac, which doesn't work if white plays well.

As a general rule, the worse the Sicilian variation is, the more dependent it is on theory to enable black to simply stay in the game and not get hammered.

I play the O'Kelly, which needs exactly zero theory that I didn't work out for myself.

The Dragon is extremely typecast and g7 is a passive square for the B. Everyone who plays against the Sicilian will have their favourite variation they play against the Dragon. GMs don't use it for a very good reason. It's passive unless white blunders badly.

Whatever you play you need to be ready for sidelines!

a6 is never a wasted move except against a KIA and that's slow in any case.

What's its use against c3?

tlay80 unfortunately there seems to be a handful of posters on this board who are insistent on giving bad information that is contrary to common knowledge. Calling the dragon a passive defence, my god. 

And yeah, just throwing in a6 in the middle of any opening... this guy is just trying to bait you. He knows what he's saying is wrong.  

I don't play ....Nf6, I play ....d5 because in c3 Sicilians I'm playing to win. If white plays slowly, black blockades the IQP. If white plays sharp, often black can too. ...a6 keeps the N out, mainly. Black needs to play it at some stage. Because a6 is played very early, I never go for the ...Bg4 variations. I think the "bishop blocked in variations" are stronger for black. Black doesn't want white to simplify to a slightly better ending.

Ignore .... he's a bit dim and he's a troll, whom I blocked ages ago..

He thinks common knowledge is anything he can understand, which isn't much.

Incidentally, I'm trying to be objective when I say that the O'Kelly move order is the most interesting Sicilian. It is because it has been completely misjudged and misanalysed by much stronger players than me, who unfortunately treat it like a one-shot wonder. They think an early ...e5 for black is mandatory but I've been playing it for a long time now, at a reasonably high level. Obviously not GM level. The strongest players I'm likely ever to face in slow-play are about 2300 FIDE. A strong player who knows his Sicilian variations will understand that a position where black has a wedge in the middle of the board with ...e5 can be very bad for black in the long run, when the position is analysed strategically, because the pawn wedge gets in black's way and black has to be extremely accurate indeed just to survive. There may be move-sequences that draw for black with best play but that's all. Essentially, white has to blunder badly and that's what black must hope for, to allow black to break out.

The O'Kelly is really a highly transpositional tool with a number of variations that belong to the O-Kelly alone, both in the open and in sidelines. That's why it is potentially the most interesting Sicilian that there is.

Some people aren't capable of understanding these things, however.

As you noted, the O'Kelly is really a transpositional tool.  It is not really a variation unto itself (as the lines that are unique to it are not all that great).  All you are really telling White is "I'm going to play a Sicilian where a6 is useful ... in other words, I'm not going to play a Dragon".  In terms of being "interesting", I would say it is more interesting for White, since he really gets to pick the main direction since Black is quite often left with a choice of going into X mainline or pick this poor sideline and suffer for a while.

And no, you are not at all being objective with your assertion.  That is completely subjective, which is fine, but do not delude yourself.  And I don't know who you've been talking to that thinks e5 is mandatory in any Sicilian, but that is hogwash.  There are ways to play with e6; there are ways to play with e5; hell, there are ways to play with g6 (although these tend to lead to very bad versions of the Dragondorf).

As you noted, the O'Kelly is really a transpositional tool.  It is not really a variation unto itself (as the lines that are unique to it are not all that great).>>

I've analysed it independently over 25 years and I think the main line which I use is superb and yes, there are lines completely unique to it.

Calm down and stop telling me what you think I am or am not being, because that is YOUR subjective judgement based on zero evidence. If you were genuinely interested, I'd discuss it.

Incidentally, why would you use it to transpose to the Najdorf, which can be reached by a normal move-order? If that's the idea you're basing your objections on, you're not on the ball. And yes, a Taimanov or a Paulsen can be played with g6, but that only comes into my lines in very unusual circumstances, often when white sacs a pawn in the opening, as occasionally happens.

The dragon is not passive, here is an example:

Crikey, white played that badly. Of course, the Dragon is a perfect weapon against such inaccurate play. But against a more careful type of player, that doesn't happen.

Name one variation that shows blacks passivity.

As I stated, you can get into lines completely unique to the O'Kelly - they simply tend to be much worse than transposing back into a mainline.

And I'm completely calm.  It is you that is getting rather riled up.  But stating you are trying to be objective about it is simply delusional.  You have your favorite variation, which is great!  More power to you.  Just because it is your favorite variation does not make it the most interesting, or even good!  I have a friend who swears by the Grob (even wrote a book about it 30 years ago!).  The fact that he likes it does not change the objective evaluation that it is a terrible opening!  While the O'Kelly is nowhere near a bad as the Grob, it has very little uniqueness to it.  It is a bit like playing 1. Nf3 - you are likely to transpose into a mainline, but you simply want to delay telling your opponent which mainline!  Such move order tricks can work against someone who turns their brain off in the opening.

I was showing that it likely transposes into almost any mainline that is not a Dragon (because a6 is not a useful move in the Dragon Variations).  And I don't really have any objections to the variation - simply to your assertion that you are being objective by saying it is the most interesting.  It is the most interesting to YOU - hence, that is a subjective assessment.  The only other objection I had was not directed at you, but to whoever you have been talking to that asserted you MUST play e5 in these positions.  e5 is 1 way to play them, but far from the only way.

See the Yasser Seirawan analysis of the Karpov-Korchnoi game from 1974.

Honestly I would like to know when you play a6 what position are you looking to play against the c3 sicilian? Is it 1. e4 c5 2. Nf3 a6 3. c3 d5 4. exd Qxd 5. d4 e6 Anything besides e6 looks to give white a comfortable advantage by simply taking the c pawn and going into the ending a pawn up. And even after e6 white looks better after 6. Be3. Or maybe it as some other position you had in mind?