As a Sicilian player with Black, I find the Alapin Sicilian most annoying. I seek to play the Paulsen or Taimanov Sicilian w early e6, so you can't play a Bb5 Sicilian against it. With the Alapin, White is trying to limit your counterplay and just get a lingering small positional advantage. The best defense for Black is played like the Alekhine defense, Nf6 allowing e5, which I really don't like.
With White, you can always play the Alapin if you are patient and don't expect to blast your opponent off the board in 15-20 moves. In the open Sicilians, Black can try a variety of complex structures. You'd get a bigger advantage with white if you know exactly what to do and have great attacking skills, but it takes a lot more know how.
The most comprehensive opening guide to the Alapin was written by Murray Chandler. GM Sveshnikov also played it with success and has written about it.
I breathe a sigh of relief when somebody tries the Grand Prix Attack. The defense is not that complicated. I know how the easy cookbook mating attack with Bc4 works, so I don't just walk into it. To surprise the Black player, you need some very unorthodox weirdness like 2 b3 or 2 Na3 or 2 g3, but that just forces Black to think for himself early and not rely on memory or habit.
I've been experimenting with 2. Qh5 lately. Having moderate success. The Siclian is quite a solid defense for black. I don't think there's a "trump card" against it.