I think it depends if you're feeding wire up a conduit out the top of a panel, or down a conduit out the bottom of a panel.
I like to set up the wire so it comes of the roll in the direction you are feeding.
If you are feeding up a conduit, I find it easier to have the wire coming off the bottom of the reel so the wire comes off the reel and feeds right up the conduit smoothly with out having to change direction. The opposite for feeding wire down a conduit, have the wire come of the top and feed right down the conduit.
It is easier (IMO) for the person feeding the wire to not have to change direction or fight against the natural curve of the wire.
Of course this is only for larger wire, pulling #12 thhn, it really doesn't matter!