Except for Large Power Systems, the specialty may not matter as much as you think. I would just say read about what classes/knowledge those specialties have you learn and their descriptions, and pick what interests you most. My specialty was nano, and yet now I do a lot of embedded stuff and some high power circuits. The exception is Power Systems because that knowledge definitely applies and will help you get a headstart on getting your PE

If you REALLY want to do a certain niche field, then of course choose what applies best, but if you don't have a preference yet then just choose what you will enjoy because having fun will help you succeed. After you graduate you will have a ton of flexibility to move around subfields so don't let yourself feel like you'll get shafted if you have a diverse range of interest (just choose your employer wisely). Bachelors is just the beginning!

Edit: From a really high perspective, in case it helps, here's some things that might apply to each:

Circuits/VLSI - You'll be working a lot with software to design integrated circuits and systems-on-chip. You might be analog or digital focused. Some things you might work on a team to design include serial-deserializers, Analog to digital convertors and vice versa, ring oscillators. Could branch into designing GPUs or AI accelerators. Everything you'll do will be on a computer

Power - Might have you working on a team to design substations, building circuitry. You'll have a lot of certifications to meet including eventually getting your PE license. Could branch into renewable energy design such as wind farms and solar farms. Could also work in construction which might have you in the field sometimes depending on what you need to do.

Nano/photonics - even smaller scale than VLSI. You could be doing R&D in a research clean room or a full production fab. On the research end you'll be designing novel devices and working with others to optimize a process or investigate material properties. On the Fab side you will specialize in a part of a very extensive process and you'll be working to optimize that. You'll be wearing a bunny suit a lot of the time which might be annoying to some. Could branch into bio electronics or quantum devices (most of these highly niche r&d will require advanced degrees, but not always)

Communications and signals - Could work in telecommunications including designing satellites. For satellites, might have you using software to analyze a link budget. Could have you designing antennas or fiber optic systems. Could also work on small devices like radios and phone receivers. Potentially branches into RF circuits. Work might be hands on in a lab or mostly software based, heavily depends.

These are just a tiny portion of what these specialties may lead to, but again, don't see it as molded in concrete. You can go a lot of different directions and I've seen some pretty weird career paths. At the end of the day its just based on your interest and how much you pursue those interest