Best Banks for Mentorship

So when reading about financial leaders and executives, a common thread seems to be that many of the most successful bankers and investors had some serious mentorship and exposure to senior executives at a young age.  Eddie Lampert had Rob Rubin, Ray McGuire had Perella, and Schwarzman had Peter Peterson.  Hell even Buffet had Graham.

From younger professionals, I've never heard stories like this.  Entering a financial career today feels like signing up to be a cog in an old redundant machine, when in contrast, this industry seemed like a place that formerly molded businessmen though mentorship and close guidance.  Maybe this assessment is incorrect, but this is just my perception, and I have been cognizant of trying to look for firms that will actually invest in me. 
That said, are the boutiques still the way to go for someone who wants to make a long term career in finance?  Are there banks/firms that still emphasize this culture of mentorship, that genuinely invest in you as a professional, and give you exposure to top flight financiers to learn from?