I was just wondering which one is easier and would give me a better mark? Has anyone personally taken CHEM 1R03 (Gr 12 equivalent)?

I haven't taken Chem 1R03, but if its the high school equivalent I would expect it to be roughly as tough as that. So its as tough as a high school course.

I can say right now that Econ 1BB3 was easier than high school Chem for me at least, probably easier than most high school courses. However, if you want to take more Chem courses at a later date 1R03 would be useful. But if you just want a high mark, go with 1BB3.