The jive isn't that different from a RPM which still has a strong following, and the siren is a a cool boat for girls. The shock doesn't look that good to me but someone probably loves it. For a first boat you need something that you can learn the basics in. Eddy turns, peel outs, rolls, setting a ferry angle, strokes. All 3 of these boats will do this. However, when you want to try to start play boating, running harder whitewater, particularly creeks, or both these kayaks will start to be limiting.
If you want to try the sport out and these are more affordable and available to you then it's a good fit for you. If you can afford and can access say a Jackson fun, a Wavesport EZG, or a Dagger Crazy 88, they will go a little bit further in your whitewater career.