Both are one dimensional and not the smartest out there on the court. Gordon is, eh or was, in a more important role with the Bulls and might be "the man" in Detroit. JR has Melo, Billups, Kenyon in front of him.
Gordon has proven he can carry a scoring load and proven he can play big minutes. JR hasnt really proven much to me outside of be a very nice spark off the bench. They are both streak and volume scorers but I trust Ben more so because I have seen him being able to be a focal point on a team.
Gordon is the way more consistent and fundamental player. On the other hand, JR is much stronger around the basket and is a better passer. I don't know how either player is defensively, but I doubt it matters. I'd rather have Ben Gordon. He's basically the 2000s Microwave. Nobody really is sure what JR Smith is yet. Most likely he's not anything. But he could blow up and be a bigtime contributor any minute. It's not like he's lazy and not willing to exercise his potential; he works harder on his game than almost any other NBA player from what I hear. (or at least, on his jumpshot.) It's just he's streaky. His accuracy depends too much on the accuracy of his last 2 or 3 shots. His ballhandling has improved but I still wouldn't really call it good. Gordon's been one of the most clutch players in the league since he got here. JR is clutch too- but only if he's been having a good game.
The gigantic difference in their free throw shooting is also a factor. I can't have my SG going 5-9 from the line in a playoff game. It's probably not a dealbreaker, but it's yet another thing that keeps JR from being as good as he could be. You kind of get the feeling all he practices is 30 footers. For 5 hours a day.