In reading your message it seems that you still have to clarify your priorities. 
You still probably don't know if the most important aspect is salary or position.
Position, in my view, is much more important. But positions is not just your job title, it is what you are asked to do and what you can learn from that position.
At MBB your learning point is priceless, you learn literally how to think.
As former special forces operational, I think that MBB is second only to special forces in terms of learning opportunities. 
So, my subjective advice is to think about what you want to achieve, what is your scale of needs and values, and then compare what you can get at MBB if compared with Tier 2 firms. 

Good luck!

MBA is valued but that will depend on where that MBA is from, specialisation (Strat, Marketing, Finance or General),  your experience & background. MBA in itself wont guarantee anything.

Most big consulting firms have very standard entry points for MBA candidates and unless you really outperform in the interview process, there isn't much room to negotiate (other than sign-on bonus and other small bits).

Rather than comparing yourself to others too much, determine where you stand currently and pay attention to what's the right move for you. Dont go too much by external factors otherwise you will end up making decisions to suit the external environment and not what's really right for you. Have a look at this article for some guidance- https://www.preplounge.com/en/articles/how-do-i-know-which-career-is-right-for-me

Haha, I had 3 years of strategy consulting experience + 3 years of manager in a corporate strategy role (+4 year of industry experience) and a Top10 MBA, was starting to become the lead strategist for a $1 billion busines unit, but even so MBB didn't want me to get in at the manager level, but just before that (Case Team Leader, which is a “junior manager”).

They want to make sure you get the right training and experience before you take on a certain responsibility. 

And you know what? I took it, knowing it was -25% of the Manager role. In hindsight maybe I could have negotiated something else, but it didn't and doesn't really matter, because I was looking into the long run.

In the long run, I would be promoted the following year (I actually left to become a Principal in a competitor, “stolen” by someone who knew well my seniority and performance).

This is not a career where you are stuck for years in the role you are hired to. You get promotions every year. If you do really well, you are promoted earlier. 

It is much more important to make sure the firm has a great brand, a great career track, supports and trains their people, and is doing well (i.e., growing). If that is the case, it doesn't matter that you have to wait 6-12 more months to be in the role you want to.

Dear candidate,

do not worry about entering at a “junior” level, instead see it as an easier path in, the requirements are much lower than if you had to enter at project manager level. The salary is usually standard, but give your career some time and you will advance also salary-wise.

Best regards,

Charlotte