It depends on what are you trying to achieve. The choice you makes MARGINAL difference and only when you are just starting out.

If prestige is what you are going for then by all means go for ICAEW if you can get a job from a recognized employer (Which are usually big corporates or Big 4s). If you want to show that you are technically savvy and you don't mind the heavy examination process then go for ACCA/CIMA. If you just want to get a professional accounting qualification and eventually obtain MIA membership, then an easier choice would be CPA (in terms of examination process). 

Once you are in the door, it really doesn't matter anymore because it is your job performance that matters.

If I were you (that is, already having CIA and a undergraduate degree in accounting), I would go for CPA or anything that is easier for me to reach my destination assuming MIA is your ultimate goal. I would have included CAANZ (previously known as ICAA which is the Chartered Accountants of Australia before it merged with ICANZ) or US CPA if they were options because I think they are also easier compared to ACCA/CIMA/ICAEW/MICPA but assuming you are in Malaysia then it is not really practical. I have done ACCA and ICAA btw (those were my choices available back then) but I have many friends who did CPA Australia and yet being very successful in their career anyway.

Some may say CPA is less prestigious but let's be practical - why does it matter as long as you get the job done? As analogy, driving a Toyota may not look as prestigious as driving a Porche but in the end, a Toyota is a practical car that reaches the destination and it is far better than driving an expensive Porche but got stuck in the traffic jam anyway - all I am saying is the qualification is just a tool and what matters is how you use it and the uncontrollable circumstances that determine your career. I have seen too many people care too much about what other people think and took up examinations that is beyond their capabilities and not progressing, whereas those who go for something easier and resist criticism went on to become Partners/CFO. The qualification does not really matter in the long run seriously.

In fact, I don't think anyone these days still hold a strong opinion about CPA vs ICAEW or ACCA or whatever. Those who does definitely have an issue with their ego and don't see the big picture.

So long story short - go for whatever that is practical for your personal circumstances and look at the big picture.

As an internal auditor. Any certificates will do. Whatever you see yup there are just accounting certs. Expand your view and look into fraud examiner, IT audit and other industry standards. Your scope is wide enough to justify any sort of learning you want.

Just as an aside, do you foresee an or any advantage an Australian CPA might offer, in terms of your plans (if any) to relocate there? I know a fair few of my wife’s colleagues who did the CPA(A) solely for that purpose!