Prioritizing sales vs ops roles at a tech company as a pathway to M7 MBA?

I'm 26 years old and currently living in Canada. I'm juggling 2 offers one in operations and the other in sales. Both offers are from unicorns valued between $2-5b. I've previously worked in both of these areas plus some mild finance exp. from my undergrad days. 

For the past few years, I've found myself exceedingly drawn to the markets, world of M&A/corp dev etc. My ultimate goal has become either TMT IB/PE and from what I can tell the only realistic pathway is through B-School.

My perceived pathway: New Job (2-3 years) -> M7 -> Summer Assoc. -> Full Time (Generalist?) -> Lateral to TMT

Based on this, any suggestions? Additional considerations:
- Did my undergrad in Economics and minored in math (UofT/McGill/UBC)
- Am a Canadian citizen (will need visa etc.)
- Will have ~6 years of work exp. at the time of application (plus internships).

Any advice would be immensely appreciated. I did consider trying to find a back office role first but those are ****** here and have no realistic pathway to a front office role in NY.