Is there a good reason to choose one lens over the other?
Granted that the 24mm lens is a bit wider than the 28mm lens but are there any other reasons?
One chooses a prime lens primarily for its focal length/field of view (and secondarily for its aperture), so the fact that one is a 24mm lens with its characteristic field of view, while the other is a 28mm lens with a different field of view is the deciding factor. It really doesn't matter whether one is marginally sharper or has better distortion or aberration characteristics than the other; the fact is that each can take pictures the other cannot.
(I suppose you could crop a 28mm-sized picture out of a 24mm exposure if the 24 is an objectively "better" lens, but are you gaining quality that way? The 24 would have to be in a whole different performance class just to balance the scales if a 28 is what you need.)
As noted in the review for each lens at the-digital-picture.com:
...focal length is the biggest and really, only, significant difference...[between the lenses]
The obvious difference is the focal length. They are similar, but 24mm will be noticeably wider. The 24mm is also 20g heavier and slightly longer(.2").
Overall just choose the focal length you like most and either lens will perform the same otherwise.
4mm at the wide angle makes a lot of difference, especially compared to 4mm at the tele angle.
My analogy is like this. Stand two chop sticks vertically next to each other on a table about 5cm apart. Now make a triangle with the top ends touching and hold it. Hold them so they cross each other and move down towards the table about 5cm.
Now cross them at the bottom and while holding the point where they cross and move up 5cm. The angle of difference is much more significant.
Looking at this:
This is because we see the focal length as a linear scale, but the angle changes at a (logarithmic) trigonometric scale.
So, in answer to your question, it depends what you want to shoot.