Depends on what the general use means. Out of the three, I'd also favour 1 (with more ram and an operating system), unless you specifically want a dedicated graphics (3 in that case).
However, it also depends on what the prices are and what you want to use the computer for. I would, for example, also be interested in battery life and weight. And if I really wanted to buy a 15 inch laptop (I prefer smaller sizes), I'd at least want a better screen resolution. See -- it's all about personal preferences and you haven't written too much about yours.
And are these the only computers you can choose from?