If they like Garage Band already, why not Logic Studio which is a “grown up” version of Garage Band?

I'd say Ableton lite is still a step up, and gives you familiarity with the Ableton interface, which means you are primed for using one of the bigger editions. However, if said 16-year-old does not currently have a midi keyboard / controller I would look at buying one that includes bundled Ableton Lite as the gift. Something from the Novation Launchkey range would fit the bill.

Ableton suite is amazing because of all the content you get with it (instruments, effects, samples), but lite comes with enough to get you going and you can always add vsts and samples from 3rd parties.

You don't usually purchase the Lite version, you get it with like a $50-100 worth of hardware from the likes of AKAI or Novation or whatever.

It has a hard limit of 8 tracks, Intro doubles that to 16, while Standard is the first version without limitations. Intro should be more than fine for most beginners.

Lite is far too limited and you can't buy it on its own anyway, it only comes included with various hardware. Intro is limited to 16 tracks, Garage Band to 32 tracks. There's various other limitations too. Ableton has generous educational pricing though (50% off).

+1 to the other recommendations to get them Standard, Intro is pretty limited for an "upgrade" (coming from a daily user of Suite).