I'll take a crack at this one, mainly because I was and am in a very similar situation. I've heard from many neurologists that they were initially interested in neurosurgery, primarily because of their interest in neuroscience and the brain, until they realized that there is not really all that much neuroscience in neurosurgery. There is a lot of neuroanatomy that must be known, and a lot of surgical technique that must be known. But knowing how a lesion is actually affecting cognition, and things of that sort, is of less importance in the field. There are certainly fields within neurosurgery that are heavier on the neuroscience aspect, such as neurotransplantation and functional neurosurgery for movement disorders, where it is necessary to known what a particular region of the brain is doing. These are the fields that I am most interested in, having a predilection for both neuroscience and hands-on procedures. However, the bulk of neurosurgery, which is still tumors and trauma, places less emphasis on the neuroscience behind the procedures. There are, to be sure, things you must utilize about the brain to preserve as much functionality as possible, but less brain science, per se.
I have been told that if you are torn between both fields, your best bet is probably neurology. I more and more find this to be true; most neurosurgeons decide they want to be surgeons first, and neurosurgery follows from that based on interests and personality. If you follow around doctors in both specialties, it shouldn't be hard to decide between the two. But having said that, look into functional neurosurgery, which is of course very hands-on, but with an added emphasis of knowing the neuroscience behind the procedures. The other area you could look into is interventional neurology, which focuses on minimally invasive vascular procedures, but with your training done through neurology. You will be competing with neurosurgeons for these spots though.
As far as robotics goes, there is not as much going on in neurosurgery vis a vis robotics as there is in OBGYN or urology. Robotics during surgery is mainly used when there are open interior spaces but tight angles that must be operated around. There is a NS at University of Toronto that pioneered an intra MRI robotic arm for neuro procedures, but at this point, the only large benefit to using it is reducing surgeon tremors. Robotics on the patient side is very active in both fields however, with computer brain interface being a hot research area. The difference between neurology and NS is that the most sensitive sensors must be implanted, necessitating the use of a neurosurgeon, while ones based on EEG or MEG are managed by neurologists. I tend to believe that there will be a point when implantation will not be necessary due to high sensitivity EEG/MEG sensors, and that neurosurgeons will play a smaller role in this research field. I could be very wrong though. Some input from attendings working in these areas would be very helpful.
So I guess my final piece of advice would be that stick with neurology unless you find yourself especially drawn to surgery, in which case you should really try to shadow a functional neurosurgeon.
