I never used either of them but rafis and kynan in their reviews of gaomon said that it is well made and the only issue they had was that the pen is heavy. But i know nothing about these tablets so it is up to you which one you want
They both use the same pen if what im seeing in correct. I don't own a gaomon but i do own a regular 420. Its a VERY fine tablet for its price. I drag and the tablet is still goin strong for about 5 months so far.