It depends on what you want the toy for. I love my Gigi but I typically use it as a clitoral massager and rarely as a g-spot toy (its too short and not curved enough to hit my g-spot). The Ella is great if you are looking for a great multi-purpose dildo. My roommate loves her Ella.
I don't have ella and have been told mixed things so I still don't know if I'm going to get it. I do love the vibrations, I just think when stimulating the g-spot low vibrations feel better than just a firm toy.
I have a Gigi, and love the deep g-spot vibrations.
It's also a really firm toy, (like the Ella), which means once you get it onto your g-spot, it's not going to flex. This is a blessing and a curse; it won't move around once you get it where you want it, but if a partner is holding the reins, it's easy to accidentally cause discomfort.