I'm a big guy (6'4, 290 pounds) like Lennie, and I especially appreciate the height and the advantages it often allows. Lennie's usually gentle nature is also a plus, but his lack of brainpower is not. George's intellectual prowess (at least when compared with Lennie) gives him a clear advantage, and his ability to control his emotions and physical responses are the deciding factors. George may never rise above his social or work status of the Steinbeck story, but going through life as someone like Lennie, with his severely limited learning capacity, would be a worse case scenario for me.
To me, there are things to be said for both sides, but I would rather be George. I think that it is the difference between being a child and being an adult.
Lennie is like a little kid. There are good things about being a little kid. You are essentially not really responsible for much so you don't have to worry about things. Lennie just goes through life letting George tell him what to do and take care of him. That is attractive in a way.
But most people eventually want to grow up and be independent. You would not want to be a child forever. I think that all people want to end up having control over their own lives as much as they can. That is why I would rather be George. Even though he has problems and challenges in his life, at least he is able to try to shape his own destiny. Lennie, by contrast, cannot even do that much.
Considering the setting of Of Mice and Men, the position of Lennie is extremely vulnerable. Without George, he cannot find work as George convinces the bosses to hire Lennie after he has his friend demonstrate his strength; he also convinces them that Lennie "will do anything I tell him," so there will be no problem with Lennie. On the other hand, George can survive without Lennie. In fact, when he is angered, George bemoans his being burdened with Lennie:
"...If I was alone, I could live so easy. I could go get a job an' work, an' no trouble. No mess at all, and when the end of the month come I could take my fifty bucks and go into town and get whatever I want.....You keep me in hot water all the time."
Of course, George only half means what he says, but he makes the point that he can survive on his own, even in the Great Depression. It is always better to be able to survive on one's own--albeit lonely and alienated--than to have to depend upon others for your survival. Make this a third vote for George, a vote for intelligence over brute strength and child-like naivete, even though without Lennie Small George has no dream.