George Harrison was an amazing, spiritual man. He had written some of the best music for the band [this is of course all opinion]. It isn't hard to see what his goals in life were from his music, either. [While My Guitar Gently Weeps, Here Comes the Sun, My Sweet Lord, Bangla Desh]. His concert for Bangladesh also shows his devotion to humanitarian causes.
John Lennon of course was a man of social change. He wanted to see the world give peace a chance, and wanted to see and end to war, enslavement and greed. But most importantly he wanted the world to love as it should. He often criticized and wrote satire on the subject of society and how his modern world differed from what he felt [and I agree] was deeply important.
Though I can't pick a favorite between the two, I will say in my opinion that George Harrison had much better post-Beatles albums.