I think you'll get a biased answer here. There are two routes to becoming a spine surgeon. Either you go through a neurosurgery residency or an orthopedic residency. Then, another year of fellowship in spine training. Personally, I would take the best guy in the area to do work on me as the end result is similiar for basic cases like lami, discs, etc...
You better think of things like: What if I don't want to do spine all of the time, what other things can I do? Do you want to be on call for head trauma or orthopedic trauma? Do you enjoy reducing fractures or doing sports medicine? What if reimbursements get slashed in spine procedures (which they will), what else can you do to supplement your income? Most neurons that do spine also do peripheral nerve work like carpal tunnel releases and ulnar nerve transpositions and brachial plexus work, but beyond that there is mostly head/brain work only to do.
Just something to think about.