I’m going to say Udall and that he wins the general by a bigger margin than Carter because it was only close due to Carter basically muffing up the entire last few weeks. But as said above, any one could’ve really won.
Having been a long time member of the House, I'm sure that Udall would've had better relations with Congress than Carter did and as a result would've been able to accomplish much more. But ultimately Udall's chances in 1980 would depend on his economic management and Iran policy.