I think those 3 corrupt Rockbreakers were pretty much the most difficult fight of the game. There were other fights that may have seemed difficult but in hindsight could have been handled better, and certainly when tackling similar battles armed with knowledge, were easier.
I actually completed all side-quests before I decided to pursue the main quest-line just before the Sun Ring vault, so I pretty much did everything without the Shield-weave Suit which I now have. This includes taking down Redmaw which wasn't really that difficult, and I must say, was also a bit sad. I don't know if I'm reading into how sad it is to kill machines more than most (pretty sure I am - but I really like that I am), but I find the narrative of Redmaw fantastic. Once you learn what the machines are, what their purpose is, then you realise this thing has been killing people and must be brought down - there's no other way - yet in a sense, all it's been doing has been trying to survive itself, in a way, it's kind of a tragic situation. I really like that, and it's subtle enough to not be played too loudly, I feel, by the writing and presentation in the game.
Just on that, I call into question the ethics of using what I call charm on machines in situations where combat is inevitable. When I think about the machines, they all coexist from an inter-species perspective - all machines see each-other as friendly in their natural state (and you find out why in the main quest line), however using charm or the corruption arrows makes them see each-other as outsiders and causes conflict between them. Sure, from a survival perspective, this can be justified, but as my stealth abilities and in-game skills increased, I tried to avoid straight-up combat as much as possible in order to leave machines uninterrupted and at peace. This becomes easier, too, as your resources increase due to missions or necessary kills, and materials can be purchased rather than harvested. I think I may have mentioned this before, but again - this made me absolutely remorseless in killing humans because slavery, kidnapping and ritual sacrifice are easy things to take a stance on, and I find this kind of moral positioning so fascinating in the world of Horizon and indeed out of it.
So anyway, I'm pretty much up to what I understand to be the last if not penultimate quest in the whole game, shit's gonna go down with Hades. If anything, it's the first time I've felt a little niggling doubt about the narrative - I get the necessity of Hades, so I don't know that its destruction is properly rationalised - it makes sense that it exists. Nevertheless, it's a climax, so I guess the game has to go splodey-splodey. I have to use this bloody Shield Weaver Suit for something.
Edit: Is the Shadow Ropecaster potentially OP? Or have you earned it by the time you can get it, plus the constant upkeep of wire to use it? I feel like once you're rockin' that Ropecaster, most battles are faaaaairly easy, to the degree that singular large machines are barely a threat - which makes large mobs a refreshing challenge, particularly when they involve two Ravagers.