I think it just depends on what you're looking for. If you're only looking for gspot stimulation and you think the shape and size of these toys will fit you, I would go for ella.
Most people I've heard from don't really like gspot vibrations/don't find it does much for them. That said, where most reviews say the vibrations of gigi shine is as a clit vibe. They say her shape allows them to hook under the clit (in a good way) and that it's quite delightful. In that sense, Gigi might be a little more versatile, because you aren't going to get much clit joy from Ella. if you like vibrations on your gspot, then gigi might also be a superior choice.
Ella can be put in the washing machine and used in the bath and shower, as well. Gigi can absolutely not.