If you prefer a plainer-grained, more utilitarian look to your stock, then go with one of the less expensive Black Walnut stocks; but if you like a stock with semi-fancy to fancy grain, with nice color contrasts - not as much as English or Circassian Walnut - then for the same money, Claro will give you a lot more bang for your bucks.
The only thing to be wary of with Claro, is that in the very fancy grades, sometimes stock blanks are not laid out properly, resulting in too much figure in the grip area - weakening it.
Fancy Claro also sometimes has a tendancy to move around a little, with big changes in humidity, and usually benefits from a glas-bedding job.
I like Claro. YMMV.