Billionaire donors love Rubio almost as much they love Jeb. Obviously, he is more willing to play ball then Cruz. But Rubio isn't really a center right candidate; other than immigration, he is a checklist hard-right candidate. The center right voters who prefer Jeb or Kasich (or Christie for that matter) aren't necessarily going to be in the bag for Marco. I think Trump and Cruz are personally heinous, but policy-wise there seems to be more to like about them than Rubio.