Having been involved in a couple of startups (with exits) and having done an MBA at one of the top schools in North America, here's my two cents:

STARTUP Adv's - learn quickly - get exposure to many different problems that need solving - get exposure to many areas of business - experience scale and rapid growth, if startup has good growth trajectory - can be provide good upside, if equity is granted and an exit / IPO takes place - can get exposure to insanely smart people if team members are really solid, which helps to grow network for follow-on opportunities and startups

DisAdv's - many startups fail - some startups have better founders / leaders to guide teams through tough times - plan on working non-stop in early days - even when startups raise initial rounds, many fail to raise follow-on rounds - work environment can be volatile with high attrition, due to demands of working in a startup (startups aren't for everyone) - startups are really, really hard to get traction with (early-on), which can be stressful for many people - there are many unknown factors in the long-term success of a startup

MBA Adv's - learn lots and get exposure to topics that you might not be interested in exploring on your own - opportunity to meet many new people who are talented, driven, and want to succeed - opportunity to grow professional network with businesses and professors - social proof of credibility in having worked hard to learn knowledge from a top school - opportunity to change career paths, which sometimes isn't as easy when moving from one job to another (without school being a catalyst for it)

DisAdv's - very expensive - what you put in, is what you get out (as far as work goes) - most MBA programs are 2 years in length, which is a long time to be out of the workforce (and learning on the front lines) - much of the material is theoretical, as opposed to practically applicable - focusing on grades is not always indicative of people's actual work performance - less importance is being put on an MBA, given the current state of the startup world

OUTLOOK - My education has served me well, but it was really expensive to pursue - I have gained an immense amount of knowledge through being involved in high-growth startups

RECOMMENDATION - Get involved in an early-stage startup and be a sponge - Become a voracious consumer of business content (books, podcasts, videos, etc) - Learn as much as you can about topics that you wouldn't normally, and hold yourself accountable to achieving certain goals with the content you're consuming