personally i use asm for all exams, but asm, actex and guo are all fine. it is not the manual that matters. you can only do practice exams without manuals if you have the background, especially for preliminary exams.
I used Guo for exam P because my background on probability was not strong.
If you want to do more practice questions, ASM is definitely your first choice. It consists of 20 PEs. The difficulty of first 8 is close to (but no less than) the real exams. The last 5 or 6 are super hard.