The Democrats are at a disadvantage by having a far more diverse party. they have to appeal to people demanding civil rights, gay rights, environmental protection, union protection, etc. they also have to try to win over the undecided blue collar voters. Republicans only have to focus on big business, anti-abortion/religious right, and people who want things to be “unPC” i.e. people who are mad they can’t be openly racist and sexist assholes in public.
But we are operating in a broken system in which a handful of swing states get to decide who becomes president. So basically which candidate has the best chance of beating Trump in Ohio, Wisconsin, and Pennsylvania.