Do you even need them?

In short, Canadian universities will prioritize your non-IB marks first. You will receive admission earlier based on your province's marks than IB marks. If you're applying for an elite program for example, Health Science at McMaster, Commerce at Queens, Engineering at Toronto or Waterloo, then an IB or AP courses in your profile would definitely help. Most of the universities in canada just care about your must and if that's what you're aming for, take neither IB or AP. Your marks will probably be higher without them considering they have harder and more compact curriculum.

Should I take IB even when I don't necessarily need it?

You don't have to be a great student already to get in the IB Diploma Program, and even if you fail, you can drop IB with little to no negative consequences. Assuming that you've become successful in the IB Diploma Program, your province's non-IB marks are likely all higher than 90+ which is what most universities care about and that's what they want.

Should I drop out from IB if I'm doing bad?

If you're doing poorly in IB, the grade hit you take in IB is not worth staying. For example, if you have an average of 85 in IB, dropping it would take you up to 95% with little effort and universities will be more impressed with a 95% average in your provincial public school system than an 85% in IB.

IB vs AP:

While AP is the harder version of provincial curriculum; it only provides you with more information in the course rather than actually helping you learn more. I would simply suggest taking AP if you're really interested and eager to learn more about a specific subject, it might take away around 10 or 5% of your average in the course but you'll learn more things.

IB on the other hand not only increases your knowledge in a certain subject, it also helps you to find the way that you would study the best by pushing you hard until you desperately find a way to take it off and that's where you'll be successful. In my opinion IB would help you more in being successful at your university of choice by teaching you how real learning is done but again, taking IB would probably lower your averages and that's why you should drop out of IB if you think you're doing poorly.

Resources

I live in Canada, and want to get into a top Canadian university. Should I take AP or IB classes?