I think whatever works for you. However Bristol search is very easy, you want questions about Separation in Air Law, your write Separation and you get most questions within that subject.
Also advantage with Bristol, they have many of the new questions in their V3 - and even though they say only study this if you have time, study them, because they will come up.
In Gen Nav, Rad Nav and Instruments we had many new V3 questions this last exams!
Bristol I way ahead, regardless of what others say. Some banks have many questions, but not the right or relevant questions.