Cruz has the best chance of defeating Hillary Clinton:
...Cruz is also a much better debater than Sanders or Clinton. She would not be able to get away with her evasions as she has so far. Cruz can definitely win.
The problem is that if the party nominates somebody other than Donald Trump or Cruz, it would trigger a furious backlash from both anti-establishment factions, who make up an overwhelming majority of those who have actually cast votes in GOP primaries and caucuses. If Trump is the nominee, he alienates a good chunk of ideological conservatives and establishment Republicans.
Cruz, on the other hand, will have an argument to make to both groups of anti-establishment voters, and the remaining group that despises him the most — establishment Republicans — are the most pragmatic, least ideological and most likely to fall in line behind the eventual nominee.
Moving on to the general election, there is the matter of Hillary Clinton. Trump's staggeringly bad polling and the general circus on the GOP side has in some ways helped to overshadow Clinton's incredible weaknesses as a candidate.
There has been a lot of talk about how Trump would go into the general election as the least popular nominee in decades of polling. But that amazing stat helped obscure the fact that other than Trump, Clinton would be the most unpopular dating back to 1984, in New York Times/CBS polling.
Clinton remains mired in scandal and is still struggling to fend off a challenge from a septuagenarian socialist who she initially led by over 50 points nationally. As unpopular as Cruz may be with most registered voters, polling shows him within the margin of error nationally — and some polls taken in the last month have shown Cruz tied with Clinton in Pennsylvania, Ohio, Wisconsin and Florida.