There were tradeoffs. The C64's were eight pixels wider, and could also be pixel-doubled but the Amiga's were 3-colour without losing resolution and were not limited in height.
The biggest limitation was that both systems supported only eight of them.
The AGA chipset supported sprites up to 64 pixels wide, but I dunno if any game took advantage of this.
On the other hand, you had a lot of flexibility and options both with what you did with the available hardware sprites (e.g. some games drew backgrounds using sprite hardware!) and how you could manage without them (using blitter objects instead).
I'd rather have lots of hardware sprites like the Genesis, in addition to the blitter. I think a lot of Amiga games felt like they ran slow, because it's a lot easier to move a sprite, than to move a blitter object.
