Everyone said the same when Barack started his campaign too.
I would normally bet on a democrat in this race, but the Hill has a track record of losing votes the more she gets in the spotlight. The polls will not look anything like they do now after the conventions.
The more folk see of Hillary they less they like her. She is most popular when folk hear little from her. There is good reason there are so few Dem debates. Wasserman-Schultz and Hill's folk know this. If she gets too much coverage before November, Trump's lead will be larger than the margin of fraud in too many states. Cruz's would not be so large and it is likely he would be losing outright.
Sadly, Cruz would lose to Hill in a general election. Oh, he has better arguments by the dozens, but it won't matter as the election will not be won with tight arguments. The MSM will tight focus on Cruz and never let go. All Cruzcruzcruz the dough-faced weenie. And every once in a while a soft focus shot of Hillary, just to remind you she is running, has a vagina, and is not Cruz. Given that he has the charisma of a 3 day old fish, Cruz won't be able to counter it. And Cruz has not Trump's ability to turn most attacks against him to his advantage by going rhetorical/sales pitch. And Cruz can't go after some of Hill & Bill's greatest weaknesses, as he has his own serial bimbo and current donation/campaign cash problems. I've already heard the non-denials of the bimbos. Clinton was better at it. And it will erode his core evangelical support, which is a bad thing for the candidate who plans on winning by rallying the base.
Like DS wrote, the polls will be a whole different ball game after the conventions. Most importantly, the MSM will not be able to keep Hill off the airwaves in their coverage of the Dem convention. That will Eddie Haskell the game board and it will be a new game.
Sanders would, despite his general cluelessness, be a better candidate for the Dems0. He has, like BHO in 2008 and Trump today, a less-defined image that folk can mold into the shapes of their hopes.
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For the tl;dr crowd:
1. Exposure during Dem convention hurts Hillary to the point she is about equal with GOP nominee.
2. The GOP nominee that can shift the focus to Hillary will prevail.
3. Cruz is incapable of #2. Trump has the best odds to make it happen.
4. If Sanders wins the Dem convention, the GOP has only a sliver of a chance with Trump, zero chance with any other candidate.