You will find this decision your most difficult. I like the Gigi specifically for its unique shape to making it easier to find one's g-spot. But it is a personal decision based upon your personal anatomy.

I have Liv and it is a nice vibrator. I chose it because I was intimidated by the flat head of Gigi and wasn't sure if it would work for me. However, I just recently was given the PicoBong Moka to review which is made by the same company and it is similar to Gigi but just a bit larger. I ended up actually liking the flat head. I think it all depends on what you are looking for. The Liv gives direct pinpoint stimulation where the Gigi gives a broader range of stimulation.
Some people find discomfort in pinpoint stimulation to the g-spot so Gigi would probably be better for those people.
The heads are the only actual difference between the two. They both have the same speeds and patterns.

I'd personally pass on both and got for Uma.

I have a comparison video of the two up if you check the product pages

They're pretty much exactly the same other than the head shape. I prefer the Liv. It has a curve so g-spotting is still easy but doesn't have the ridge the Gigi does -- which for me tends to catch and be painful. A lot of people really, really love that ridge and head, though, so it's totally up to what feels good to your body.

You can't really go wrong with either if moderate vibrations are enough for you. If you need a stronger vibe, I'd suggest something from JeJoue or Jopen, instead.

As CarrieAnn said, if you are looking for power... get a Jopen. Their vibrations are nicer.

If you cannot decide which one you would prefer, I'd say get the Ella, play with both heads a bit, then if you like the flat head, go Gigi. If you like the more tapered end, go Liv.

My wife likes the Gigi cause of its size and its ability to hit her G-spot. She likes the material and how it is shaped. She thanks me regularly for buying it for her.

I got Gigi but don't like it. It's beautiful, pleasing to hold and look at but it doesn't do the job for me, it's too weak and the buttons are so easy to change, I put it to off a few times. It stays in it's box full time now.

I only have Gigi out of the two options given, but I personally prefer Uma. That's the toy I judge all toys by. With uma you get very strong power and you can use it internally or externally.

I second trying the Ella, or at least reading some reviews for them. Then you can see what the curved end and the pointed end would feel like. I have an Ella review up if you might find that helpful.

we have the gigi, I wrote a review on it. check it out. the gigi is a high quality toy, aimed at pleasing her g-spot.

I have Liv and love it but mostly for clit play so if you want mostly g-spot go for gigi.

To me, the gigi is so damn versatile. It's amazing for clitoral vibration, but it's got the g-spot shape as well. Not that I even like g-spot vibration, but hey, it's got the option.