I have read some of the older answers of ranchers and found that ePractice labs has some questions with wrong answers. However, some have also mentioned that some of the question of this directly coming in exam.
I am also confused in this front. Do you have idea about the Whizlabs simulator? Very less suggestion for this.
The new web services training lab is better quality than older one. You can try oce web services training lab if you are planning to take oce web services exam. Whizlabs scdjws simulator also good, but they provide only mock exams whereas in epractize kits you can find training guides too.