The Shearwater Teric is far better dive computer than the Garmin if you are looking at something in that size and price range. On the other hand, the Garmin is a far better advanced fitness watch.
But if you are happy with the features of your Apple Watch, then I'd suggest sticking with that and getting a dedicated dive computer.
If you want all the bells and whistles and don't have any trouble paying for it, the Teric is unbeatable in a watch-sized computer. But you are looking at $1150 for just the watch, $1545 if you want the transmitter to make it AI.
A more reasonable option for both you and your daughter would be Oceanic Geo 4.0 for $400. It has everything you actually need in a dive computer, an excellent record of reliability, and is pretty stylish for a DC. The one luxury feature is a Bluetooth connection to a app which lets you download your dives for easy logging. This is very nice for new divers since maintaining logs manually gets old fast and a lot of us end up abandoning the attempt.
There is a middle ground of the Shearwater Peregrine for $600. It's non-AI like the Geo, but has a really nice color screen and a superior user interface. One potential drawback is that it's quite a bit larger, you'll need to decide if the form factor works for you.