Reneging in Consulting 😬

Hi,

Over the summer, I interned at a somewhat well known management consultancy in London and I quite enjoyed the internship. Great culture but the type of work was more technology implementation than strategy consulting. I received a return offer which had a 1 week deadline to accept, so I accepted it. However, I recently received a FT offer from a T2 strategy consulting firm (OW/LEK/OC&C/S&). I feel like their work is more aligned to my interests, the pay is similar initally but the T2 will pay substaintially more in the long term. Culture wise I really liked the management consultancy, I get along well with the partners and the incoming analyst cohort, but feel like the T2 would open more doors to potentially MBB in a couple of years.

But I'm a bit worried about reneging - the T2 interviewers frequently mentioned that they've done some work with this management consultancy in the past and know some of the partners. If I choose to renege, what would be the best way to go about this? A couple of incoming analysts will know the firm I'm reneging for as they know that I had final rounds there. What are the chances this consulting firm reaches out to the T2 and tells them I reneged and what are the consequences of that? They aren't recruiting much this year and they were very supportive throughout the internship so I dont want to put them in a bad position by reneging.

Slightly wish I had never got the T2 offer aha, the stress of deciding what to do is so much so would really appreciate any help :)

TLDR: Interned at "T3" firm in London, enjoyed it, got return offer and accepted it but the work is less interesting than strategy consulting, and pay/exits are worse too. Got a T2 FT offer - worth reneging on T3? If so, best way to renege? Consequences of reneging?