I have the Seduction and I lovvvve it. I didn't think it would be such a winner for me but it's quickly made its way into my most-used vibrators collection. In my opinion the silicone is definitely the way to go instead of the plastic - a lot of those shapes seem a bit much to consider in a hard material. The softer silicone is perfect. The shape of the Seduction is really nicely filling, I tend to use it for g-spot pressure more than for fully inserting. That said, it is nice either way and while I didn't quite understand the shape before this toy was gifted to me I totally get it now
I don't have any of the others so I can't say comparison-wise, but I can at least vouch for this one. The Delight looks fairly similar in shape with just a bit more texture so if I had to choose again it might be a toss-up between the Seduction and the Delight.