Staying in Spain is a good idea, as long as every human being needs socialising and your closest group of friends and family will be around. Moreover, your relatives may let you live at their home temporally if your salary is low. Besides, even having received no scolarship, most of the expenses caused by academic training of Spanish citizens are sponsored by the government so they should have an impact on your the same country.
However, moving abroad is considered the best option for other people economically, culturally and even professionally. First, higher salaries allow you putting away more money for your future. Then, living abroad can offer you knowledge of other ways of life. The former, more interesting positions can be found on a broader working market.
In conclusion, although there are undoubtedly pros and cons for each position, I feel strongly that to get self fulfillment there's nothing like finding the best position for you and knowing other cultures by moving abroad.