Hi Ray, congrats on your offers!
I guess in general I would choose to take SCB IG as it is not just about working on "retail banking", while for IG you will be exposed to the below-mentioned streams which can earn you an attractive career as well:
Source: SCB IG Website
About Risk Consulting, you may find the name itself much more attractive, but the truth really really depends on which part of Risk Consulting work you can do. Remember, having a risk consulting title may help you to find an in-house job, but again it is for back-office roles. The upside for it is that you may be able to find a risk position in globally-renounced financial institutions, and in most cases, the exit path would be standard banks as well.
I guess if you decided to take the offer from SCB, I highly do not recommend you to take the offer from the Big 4 first as it somehow creates troubles for the HR and the dept as it wasted their time to find a replacement. Please go ahead with SCB directly if you figured out your choice.
About the grade, "Associate" is basically the standard offer for an IG graduate. You might see the title of "Manager" as some refer it to their external client-facing title, or it is their job function that is named "Manager". So I don't think it is a case of different programme graduation offers among different IGs.
Hope the above helps la! If possible, please allow me to invite you to share more about your interview exp so that we can help future graduates on their job hunting...please!!