The benefits of your submitting to these directories depend on too many other things: what kind of directories those are, whether they belong to your niche, etc. If you consider both worthwhile, then I can't see why you should limit yourself to any particular option.
Well, I'm limiting myself to an option because I don't want to create something which won't work or will work little. Neither do I wish to created two different sites belonging to the same category having little key difference (paid/free). Remember the saying, too much of too little brings no good. Most likely, I will have to sort it out to offer both paid and free directory submission if I'm going to go with this business.