I would answer this question in a different way. I think all three are fine options and you will gain a good skillset with the several months. However, the difference between one versus the other (a few months worth of work) will not be super important in the grand scheme of things.
Rather, if you are considering joining that company afterward, pick the team you get along with the most and the person who you think is the best manager.
If you're unsure whether you'll join the company, but want to work in an area, then I might pick based on technology choices. This will be a much more important decision (your first job) than an internship area at a company (let alone an internship company) then.
Source: I've worked at Uber for 4.5+ yrs now. I'm technically a TPM manager in engineering, so not an active engineer. But I signed when our eng org was ~150 (it's over 3k now) and started off in data science, where at the time there was no hiring distinction between the two roles. So I've seen a lot of progressions (or lateral moves) of many dozens of software engineer friends over the years as well as working directly with them. Which includes people who went from new grads to senior engineers and even into management in one case, over 4 yrs.
Conor recommends the following next steps:
- Try to talk to the managers for each and ideally meet them to avoid picking a team based on the technologies they're using.
- Pick your internship area based on the experience of the manager, your perception of how good they are at it and how well you'd get along with them, and then meeting the rest of the team if possible.
- If you can't talk on the phone / visit in person, then try to get their names plus other teammates and find out what you can.
- It might sound unusual to do and there may not be much flexibility depending on how big of a company but I think they'll appreciate thoughtfulness in you picking your area based on your manager and the rest of the team rather than the tech. Since again all have good prospects for careers afterward plus with that several months you could always do something different after your first year on the job so it'd be an easy 'mistake' to fix if you found it boring.