They're indistinguishable in quite a few matters - the Bush, Obama, and Trump administrations all continued the PATRIOT act, warrantles wiretapping of US citizens, all the foreign wars the US got itself involved in, and none of them closed Guantanamo, reduced immigration, broke up any monopolies, or even slowed their mergers. And these are the topics on which they made wildly different promises. The only stand-out was Trump stopping the TPP.
I'll grant you there are other topics on which they differ, but depending on what you look at, your options quickly blur together.
See my other comment. https://news.ycombinator.com/item?id=21207421 If you care about queer rights at all, they're like night and day. There's also clear differences on abortion rights and freedom of (and from) religion.
I don't disagree with anything you said, either. It sucks, and I said so. People are reacting like I said the Democrats were nearly perfect, and I'm not sure how anyone got that from what I actually said.
I'll grant you there are other topics on which they differ, but depending on what you look at, your options quickly blur together.