What do you love through online marketing?

Your question is not very clear Ahmad.
However, I will be answering your question from how I understood it.
As someone whose tasks involve online marketing, what I love most is the dynamic nature of it.
By dynamic, I mean every changing.
Of course that also poses challenges, you need to be updated on how to overcome those changes.
Whether its changes on how Google indexes its search results- thus making you change how you can overcome it and share your content better, or changes on popular social media platforms.