If you want to retain ownership rights in your trademark, then licensing may be the best option. However, if you are looking to sell your company or are no longer interested in keeping the trademark for other reasons, then selling the trademark may be the best option.
Licensing offers long-term capital, but at the cost of regulatory paperwork and the trusting of an outside entity to protect the brand from being sullied, whereas selling involves a nearsighted, one-time profit and the loss of a lucrative identity you have spent years building.
While selling intellectual trademark property can be a great way to make an instant profit, you must take into consideration the value of this one-time sale over the potential lucrative multiple payouts that comes with licensing.