How important is the MBA brand?

Did you mean to say not very useful afterwards (after you have a track record investors care more about that rather than your MBA degree)?

it would help, but it is a nice to have. Look how many of the superstars never went to business school

Getting into top 5 finance schools is definitely great, but for other schools its important to look its at its alumni network and corporate connections. Check if the companies you want to work for hire on campus, contact a company representative who's involved with recruiting if possible, and see how many of the schools students get the jobs you want. That's the bottom line. If the school is in a major finance center and it can compete successfully with rivals, or has no rivals, then chances are you have a fair shot at your finance job. Once you get into the workforce, the MBA brand starts to matter about as much as your undergrad mattered when you started your first full time job.