Even they thought Superman and Lois was dumb and they only have books like Kingdom Come, Birthright and All-Star Superman (I like Superman's characterization in it) to their name.
They don't even interact in their solo books (outside of Superman with Lobdell that one issue where Superman became all Bella) so it would be hard to maintain a romance between them.
Need not to do more saving but also protect her whenever needed.
Now it was stated by some of the DC Comics writers that they 'could' end their relationship prior to what will happen to the world with their break up.
I think Lois is a more interesting character than both Superman and Wonder Woman, so I guess I'd pick her. Before this relationship with Diana, I looked at the other women in his life and said "Please DC! She didn't fall in love with plain Smallville Clark, but with the godlike being that was Superman.
I was not a fan of Superman being with Wonder Woman, but I've enjoyed every issue so far with them, so I'm just going to enjoy the ride, until he gets with Lois. Lois Lane would have incredibly interesting stories to write in Gotham and it would be a completely different challenge for her as a Pulitzer Prize winning reporter. And when I thought about those two I couldn't even imagine what they could have in common, what she had that actually was useful for Kal-El.