Suppose it depends what you're going to be using it for. A Macbook Pro gives you, amongst other things, the option of a more powerful processor and better graphics card than you'd get with a standard Macbook. If you don't need the extra power then go for the MB. You also have the option of 13", 15" and 17" screens. Again, if you don't need a larger screen then you can save yourself some money with a smaller display.
If you're trying to make your money go further and you're fairly competent with computers then you might want to select the MB/MBP configuration with the smallest HDD and smallest amount of RAM and then upgrade it yourself as I'm sure this is cheaper than getting Apple to do the work.