Trademark Registration provides you with compelling evidence that you are the one true owner of your trademark. It entitles you to stop others from using the same or a similar Trademark. In addition, if a Registered Trademark is infringed, the law assumes you are entitled to money damages.
If you have not registered your Trademark, it is extremely difficult to stop others from copying your trademark. You must prove in court that you are the only entity entitled to use the mark, even though you have not registered it. And, even if you are successful in establishing your right to the Trademark, it is very difficult to receive monetary damages or reimbursement for your legal fees.