More toxic than whom? I mean, if you're reaching for a comparison between the worst you can think of on the left and a moderate republican, then that's obvious. You've compared apples to hand grenades. But if you're trying to compare, in broad strokes, a group of people who hate conservatives and a group of people who what progressives, then you have to take a look at the reason why.

People who hate conservatives generally do so because they perceive conservatives as advocating policies restrictive of liberty and expression based on supposed cultural values. People who hate progressives tend to do so because they perceive progressives as threatening their cultural values on the basis of policies that supposedly expand liberty and expression beyond morally acceptable limits.

The latter is more toxic because toxicity in a democratic, law-governed society refers more or less to the availability of open political space for free expression and self-determination. Conservative media outlets have reframed a lot of this debate by revising the definition of freedom. It doesn't refer to a practice that prioritizes an open space for the exchange of ideas. It refers to the cultural values of that group, to the exclusion of other sets of values. This is usually the case with most forms of extremism.