I loathe them both...but from an electoral standpoint, with Cruz you know what he's going to do. He's a politician. He's predictable. Trump is a lose canon. He'll fire in any direction at any time. He'll say something on Monday, reverse it on Tuesday, and create a faux outrage on Wednesday. He's harder to pin down. Cruz, you know what you have. There aren't going to be any LOL voters for him.
Cruz is a worse dude, and probably easier to beat for reasons you stated. And Susan Sarandon wouldn't have Trump to vote for so that's a plus!