Which sentence is better?

Comma. It’s nonrestrictive.

However, I’d advise you to take another look at what you’ve written. The construction with “such as” says that what follows are examples of students’ weaknesses. More advanced readings and harder math problems are not weaknesses. Rewording is needed, either to give examples of weaknesses or to position those as examples of plans, not weaknesses.

Exactly what @Jeruba said, in both cases.

You got a very solid answer to your grammar question but since you said feel free to edit, I will instead address what I perceive as the message you may be attempting to convey. What you are asking here seems to be part of a resume or response to an inquiry to your skill set and or intent as a potential tutor.

In both examples you express what you like most about tutoring is to address students weaknesses and give them more advanced problems to solve. That to me comes across a bit harsh as I would think a tutor there is to make things easier for the student not harder.

I would re-phrase this thought as…“Being a tutor affords me an unique opportunity to assist my students to engage their studies and achieve levels of success they may have thought they could not have attained on their own.”

I think the sentence is too long:
What I like most about being a tutor is creating plans to address students’ weaknesses. These plans include setting more advanced readings and harder math problems.

Regarding the grammar I have nothing to add to what @Jeruba said.

Expanding on what @Cruiser said, there is something illogical about giving advanced work to struggling students. I think what you intended to say is that you like to create plans that aim to strengthen areas where a student is having difficulty.

I think the comma decision is trivial (either way is fine). But for God’s sake pay attention to the gentle advice from Jeruba and the others. You lay that sentence in front of anyone considering you for a tutoring position at risk of considerable embarassment.