I'm a long time committed axiological hedonist and have never believed that pleasure was objectively commensurable with suffering, and I also strongly suspect (but could be wrong) that pleasures are heterogenous and therefore not all pleasureable experiences are commensurable with each other (and the same with suffering). I find this makes it easier to explain clear cases of ambiguity in ethics, because I think ambiguity is baked into the axiological ground truth. I do believe that some things are objectively good and some things are objectively bad, but there is no universally accessible objective utility function by which you can rank all things from most to least desirable. Recognizing this clarifies weird edge cases where one form or another of utilitarianism seems to lead to a bad result, like symmetric utilitarianism leading to the repugnant conclusion or negative utilitarianism implying that we should destroy the world. These seem to be examples where maximizing hedonistic utility functions leads to bad things happening, because they are.
Axiological hedonism follows logically from materialist metaphysics and empiricist epistemology. Good and bad are qualities of experiences rather than external events or objects, hence why reasonable people may disagree whether or not a song was good. One person's experience of listening to the song was good, while the other person's experience was bad. Projecting qualities like "good" and "bad" onto things besides experiences is to mistake the map for the territory. And if anyone doubts that pleasure is good then they just haven't experienced the pleasures I have.
See the Theories of Well-being chapter at utilitarianism.net for a detailed philosophical overview of this topic.
The simple case against hedonism is just that it is bizarrely restrictive: many of us have non-hedonistic ultimate desires about our own lives that seem perfectly reasonable, so the burden is on the hedonist to establish that they know better than we do what is good for us, and - in particular - that our subjective feelings are the only things that could reasonably be taken to matter for our own sakes. That's an extremely (and I would say implausibly) restrictive claim.
When you say "what is good for us", could it be translated as "what we are attached to"? If you care about knowledge or relationships, you will experience (dis)satisfaction depending on what relevant events happen in your life, and you will be motivated to achieve goals related to these things, but this is a far cry from what intrinsic value means in my view.
In essence, when I say suffering is intrinsically bad, I don't mean that it is bad for anyone; I mean that it is bad period. The badness is an inherent feature of the experience.
So from my perspective, the non-hedonist is making an extraordinary and unfalsifiable claim when positing the existence of non-experiential goods.