Largely down to preference, of course - some people hate the look of a wired computer and some find wireless unreliable/fiddly. I've used both and prefer wired - the wire isn't too obtrusive-looking (the front end of the bike is full of brake/gear cables anyway, one more cable doesn't hurt IMO) and you only have one battery to worry about replacing, and interference/poor signal isn't an issue. Plus, wired models tend to be cheaper, for a given feature set.