Meh...it's alright. An overused, typical name but still decent enough. A name I can tollerate but don't think is especially superb.
My preferred spelling is
Jeffrey. It's the one I mainly grew up with and the one I'm most firmiliar with. I tend to like names whose visual aspect matches its sound even if that spelling happens to be the original.
I don't like
Jefferson. Too pretentious for my taste. Though I do prefer '
Jeff' above the others.