The answer to that kind of framing isn't to show how good the dems are, but how bad the Republicans are. Again, the dems are not interested in appealing to leftists in any way, so again, this kind of posturing is what encourages leftist voter apathy.
If a leftist says both sides are the same, show how much worse Republicans treat anyone that isn't a cishet white male over the age of 35, and how legitimately dangerous they can be for our loved ones that aren't in that category, even if they are.