Deciding between Credit vs Macro (rates, FX) quant roles

Hi all,

I a PhD student with a Math/Machine Learning background. I have 2 potential offers (one is yet to be formally received), from 2 different BB Investment Banks, and I would appreciate any help when deciding between the two.

1) Flow and Structured Credit quant role at Citigroup

2) A quant desk strat (rates ,FX and emergency markets) at Morgan Stanley.

Both are FO roles and I enjoyed the process with both the places, and all people seem nice and super smart. The 1st seems to be more relaxed compared with the second. I also heard that credit has more Machine Learning applications than rates but rates potentially has more interesting math and complicated models (which is a good thing). But given my ML background, I would like to have some ML based work too. I don't have much a finance knowledge to decide if any asset class offers better career prospects in the long run. I would like to have options in both the sell & buy side open for the medium to long term future. 

Any opinions are appreciated