Should list my advisor as an author on a paper I wrote alone? As a part of my PhD project, I wrote a paper. When my supervisor read it, she said “it is perfect and complete, go ahead and publish it yourself because I cannot contribute more to it”. She really meant it and tried to do me a favor.

However, I still think it can be more beneficial for my future to have her name on my paper. Should I insist to have her as a coauthor or it might be useful in the future to have all the credits of a good paper?
You should be a sole author for two reasons. First, your supervisor did not contribute to the paper. Some journals actually make you write out what each author accomplished, so you would be at a loss there anyway. Second, a sole-authored publication will demonstrate that you can work independently, which looks great to faculty search committees! When you are on the market, they want to hire people who will become independent researchers. You are demonstrating that by sole-authorship! If you want to publish with your supervisor because she is well-known in the field, my suggestion is that you talk with her about an additional paper project that both of you can work on. 

On a side note, your supervisor might have described your paper as "perfect and complete," though this is only one reviewer's opinion. Though the paper may be at a stage for journal submission, please be prepared that the 2-5 blind reviewers may have different opinions about what is "perfect and complete." You still may get A LOT of revision requests from them. I'm sure you did a great job, I just don't want you to get discouraged if the reviewers end up being more critical. 

Best of luck!!!!