I think for slow speeds the smaller engine will almost inevitably win, so I'd go for the little CBR or, even a bit smaller (also somewhat weaker), the CBF125. If you'd like to go 2-up much, or mostly out of town, you may better off with at least a 250.
I, personally, chose an even larger because I commuted over a freeway that time, and I fell in love with the F650CS. After I found it a rational choice, of course. The fuel injected models have an appetite very much like a 250. At least they drink less than the GS500. The mentioned 125s are, of course, better in this respect.
Note that this is my first bike, there's nothing wrong with choosing a larger one to begin, it took some time to get used to the weight, but these singles are well-mannered and predictable so their behaviour is not a problem
