Which X-Box 360 Model should I get?

I was looking into getting a X-Box 360 and the game Black ops, but I do not know which one I should buy. I want to get a slim, due to how much better it plainly is, but I do not want to spend a lot of money for it either. The arcade is cheap, but has a low amount of GB, which is no good for me. The Elite seems like a good choice, but it is not all that much cheaper. Which is the best one to get for me? I want to get one that is good, yet not use a lot of money buying it. What is the best choice to get?