I buy both.
I like the ease of using chili powder, if you find a brand you like (I like Gebhardts) it makes a quick seasoning rather easier.
I also keep chile powder, which is powdered chiles, of a few different types, for when I want a specific flavor. These are pure powdered chiles, no additives or other spices.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."