Apple watch

Make sure you scroll all the way down. Some advantages of the 6 over the SE include:

• Always on display
• Blood oxygen app
• ECG app
• Has a newer optical heart sensor
• Faster processor
• More colors available and in more metals than just aluminum

Then really any of the options would be okay. Here's a site to compare the differences between the current models.

Apple Watch - Compare Models - Apple

Does she have her own iPhone or are you going to be setting it up with your iPhone? What features are you looking for and how old is your daughter?