I have both the Jollie and the Little Su and love them both. Anatomically both work exceptionally well so long as you realize you're not going to be able to do vigorous thrusting and still hit all your spots. They both require the ability to get off just from a full sensation along with rocking/humping to stimulate both g-spot and clitoris.
The Ella is awesome for those who are just beginning to explore g-spot sensations and g-spot orgasms, but what I love about it, is that it can be used by seasoned squirt "pros" as well.
The Curve is really dependent on like or dislikes of it, by the woman using it. I've heard many women think that it was designed by a man with little to no experience stimulating the g-spot, so maybe that's why it's so hit or miss, as with the Ella, I have yet to hear of a woman who disliked it.
Have yet to try the Delight, and I have been lusting after it for a bit.
I voted for the Curve and the Ella, because I own them and know they work, as well as the Jollie and the Jollet, because the reviews confirm that they work, and the Delight, because other toys of its shape have worked for me.
I made my votes based on what I would personally consider buying first. I have an angled share toy and it's awesome. I'm super curious about the curve. It has a certain sleek and girly appeal that I like.