Arthur probably would have won.
Both Cleveland and Blaine were tainted by scandal during the campaign. It was probably the meanest and nastiest campaign EVER!
Unless Arthur's Bright's Disease was made public, Arthur would have won in a 1872-like or 1896-like victory.
On a side note: IMO Arthur was probably (after Hayes and Ford) the most underrated president of all time. Agree?
I'm not sure I would say he was
the most underrated, but he has been consistently undervalued over the years... including by his own party, who denied him the Presidential nomination in 1884. Hayes I think is vastly underrated as well, mainly because of the shady circumstances over which he achieved office. But his performance once there was first-rate, and again disdained by his own party. I don't see why you say Ford is underrated... I think, if anything, he was overrated, and one of our worst presidents.
Arthur may well have won in 1884. He had a somewhat shady past, but he had made up for it with a clean and fair-minded presidency, so he wouldn't have had some of the problems with his past dealings that Blaine did. And the election was decided by New York, which Cleveland carried by a razor-thin margin. If Arthur had done as well in the rest of the country as Blaine did, but a little better in his home state, he would have won, and it's reasonable to assume that he might have done so.