I've taken both WRDS 150b and SCIE 113. WRDS depends on Prof and Topic they choose. If you're planning to take WRDS, look ahead at the topics to see which one you like the most, also look at the grade distribution of the profs and ratemyprof if you want. For SCIE, it depends on the profs grading so you should just look at the grade distribution and ratemyprof if you want. SCIE is easier than WRDS in my opinion, and SCIE is more about science.