I don't think there's any way to avoid suppressing speech, it's who we allow to suppress speech, and the speech of whom, that varies. I also thinks there's a finite space for speech, so there's zero-sum competition to a degree, and many of the ways speech suppresses other speech is not through anything most of humanity considers virtuous (i.e. truth).
So the usual standard is that larger entities, usually governments, but also certain large companies and societies, like ISPs, aren't allowed to suppress speech, and have to let other entities under their influence suppress/censor themselves instead (not actually possible, since every action they take will suppress someone under their influence). Smaller entities, especially individuals, are often described as expressing freedom (of speech, association etc.) when they suppress their own speech, or others. This often leaves blurred lines for entities in-between, such as universities, as to whether they can suppress/censor or not in various situations.
I think the best way to deal with this issue it to pick an agreed upon metric, and then test that metric against any of the systems you want to apply to speech. So diversity of ideas, truth, personal freedom and similar metrics are often used, and the test is relatively straight forward from there.
I think the worst way to test these metrics is to simply look at the law of a country, since that has little impact on how speech is actually flowing through it (so many countries claim to guarantee free speech, for example, without clarifying, and then outlaw defamation and obscenity to various degrees, enforce intellectual property, and censor parts of internet). The two countries I'm most familiar with on this, the UK and US, whilst being very good relative to a lot of the world, are very deceitful with their definitions of free speech, and regular suppress speech outside of zero-sum necessity, and their own rules of what obscenity, defamation and intellectual property are. They both value different parts of speech, protect it accordingly, and then pretend this makes them superior to other countries who have different values surrounding what speech they try to protect the most.
