Although we all think at some stage that flying bigger is flying better, the real difference between one job and another is
Lifestyle.
With similar types, of course this is not part of your question but in my opinion, even if it was, it shouldn't make that much difference.
So best to establish what life you want for the next few years. Perhaps a bit of adventure would suit you, in that case RBA could be a nice change from the European life you know.
Or if you already have kids and family (or short term plans), you would be better off staying in Malta/Europe.
Perhaps you should also consider the stability of the currency you will be paid in, cost of living, saving possibility, career prospects.
Then again chances are, because it is your first airline job that you end your career with either of them so you might want to go for the one offers the most diversity/fun etc...
In any case, you can't go wrong because once you have a Bus or a Bong on your licence, you will never be in the situation you have been in until now.
If it was me, I would go for the sunny place so I can have my boat moored not too far and use it most of the year.
