While I do not know your personal circumstances, from a purely objective lens MBB is way more valuable than EY. There is a reason people want to get into MBB vs Tier 2 and as you probably know, the exit opportunities are much better with MBB.
In terms of career growth, from what I know it is a lot more defined at MBB - the routes are clear and there are set goals to achieve to get there. Once you get to AP of course making partner is more about networking etc. However in EY I have seen this is not always the case and a lot more politics is involved.
All the best,