I used to use Paint Shop Pro for (among other things) pixel art. Somewhere around version 6 JASC decided it was no longer a generic graphics package but should be a Photoshop-rivalling photograph editor. From then on, selections no longer had crisp edges along a pixel boundary but took the edge pixel at half alpha and the next pixel over even more transparent. I couldn't find an option to turn this off anywhere. Goodbye, ability to do pixel art in PSP.
I don't think Photoshop does this (I haven't used it for several versions and my art days are more or less over) but the above has made me forever slightly wary of attempting pixel art in a package primarily sold for photo editing.
Plus, Photoshop is expensive. If you have it anyway and it works for you, that's cool. If you're looking to install something just to make pixel art, you're spending a lot of money on a lot of features which are irrelevant to you and may make it harder to find the functions you actually need.
I still use PSP 9 for bitmapped/raster graphics (other than photos), and had used all of the versions from 3 on except 8. All you needed to do was to uncheck the "antialias" option box (and make sure that the feather value was at zero) to get a crisp (no alpha) selection. The setting were persistent, like a preference, so once you deselected the "antialias", it became the default until you selected it again.
I don't think Photoshop does this (I haven't used it for several versions and my art days are more or less over) but the above has made me forever slightly wary of attempting pixel art in a package primarily sold for photo editing.
Plus, Photoshop is expensive. If you have it anyway and it works for you, that's cool. If you're looking to install something just to make pixel art, you're spending a lot of money on a lot of features which are irrelevant to you and may make it harder to find the functions you actually need.