Hi Emilio95,
Assuming the schools to which you plan to apply equally weight the GRE and GMAT, if you find you excel at the GRE, then there is no reason not to take it. That said, the next thing you should do is take a full length ETS GRE practice exam so you can get a beeline score. You can find the exams here:
https://www.ets.org/gre/revised_general/prepare/Once you take the practice exam, feel free to reach back out with any further questions.
Lastly, this article contains some helpful information regarding the differences between the GMAT and GRE:
The GMAT versus The GRE