I'm currently using Aviation Exam and ATPL online but wondering whether to drop ATPL Online in favour of Bristol for my next set of exams. I wouldn't ideally want to be using three QBs as it seems a bit excessive!
Here's a radical idea, rather than try to memorise the contents of three question banks, why not put your effort into a text book? It will give you a far better depth of knowledge, which will come in handy at any interviews that come your way. When you're flying, you don't always get four options, two of which are clear nonsense anyway.