Sicilian or caro kann
Doesn't matter. They are both fine. It is more important to learn some chess (tactics, strategy, endgame). Openings are for old people (like me) to have fun with, when they (we) doesn't improve anymore.
So the Caro kann is easy to learn got decent play against all vartions an is overall super solid
MY ANSWER Sicilian is technically better but still only if you are a Gm
There are ~13 or so different mainline sicilians that are viable... some are theoretical, others are very uncommon... how they play varies alot, you really can't make alot of generic true statements about the sicilian. And black chooses which of the main variations to enter. In the CK white has most of the control over which line is entered, this is the main thing I dislike about it. It simply is not correct that the sicilian is for GMs and no one else - maybe that's true for the Najdorf or the Sveshnikov, maybe... It's certainly not true for something like the four knights, the taimanov, the accelerated dragon.... and many other sicilians
So the Caro kann is easy to learn got decent play against all vartions an is overall super solid
MY ANSWER Sicilian is technically better but still only if you are a Gm
I personally prefer the caro kann as it's simple and it works. If it ain't broken, don't fix it. Just last year, Vishy played it against Nepo, MVL, and Aronian and reached a draw in those games. It just goes to show that it's still unbreakable even at the top level.
The reason why top GMs love playing sicilian is because it's a more complex opening. It has so many lines that it challenges your opponent's opening theory knowledge.
Caro kann is a simple opening. However, it is more straightforward than Sicilian so it has been studied quite a lot.
So at GM level, caro kann is still effective without doubt. However, these people are aiming to be the best. Caro kann, while safe, there's very little play to catch your opponent off guard. Nowadays, it's safe to assume that GMs only play this against other GMs if they want to play safe or if they're hiding more interesting lines that they want to keep hidden until the next big tournament.
I'll also note that at it's core, they're very different openings.
Caro kann is an opening that was meant for more theory-based chess players to fight against the more tactical players. An example of this is Tal vs Botvinnik. It was Botvinnik's main weapon against Tal. Botvinnik managed to score games against Tal by trying to smother his tactical superiority with a rock solid opening.
Sicilian, due to it's more complex lines, is more explosive and is better played by more tactical players. That's also the reason why it's recommended only to learn if you're an advanced player.
So if you're a chess player who relies more on theory, caro kann is probably a more effective opening. If you have confidence in your tactics, sicilian is a better choice.
Caro kann is great until higher levels where your opponents don't make mistakes and you need to play more provocative and tactical openings to get winning chances.
Its the reason why the higher you climb, the less you see the london. opponents know what they are doing and they just equalize really quickly
A nice bonus to the sicilian though is you can get games like this: https://www.chess.com/forum/view/game-showcase/take-a-look-at-this-amazing-dragon-sicilian-game
Caro kann is great until higher levels where your opponents don't make mistakes and you need to play more provocative and tactical openings to get winning chances.
This sounds reasonable. However, we'd need to define just how high these "higher levels" are, where opponents supposedly don't make mistakes anymore ...