At least when it comes to a HG or COG, having a MC gender-locked to female and usually also a MC gender-locked to male, will be a deal-breaker to me.
While I can sometimes switch things around for some of my plathroughs in some HGs or COGs and play a female MC in order to explore some romances or some options that I don’t feel comfortable exploring with my male MCs, I do greatly prefer having a male MC. And it’s important for me to have to the option to choose the gender of my MC, to be forced to always play a female MC in a HG or COG would just feel much too constricting for me.
The main problem I have with HGs and COGs with a gender-locked to male MC on a personal level, is that the MCs of such HGs or COGs are usually the kind of MCs I dislike the most to play as a male MC, that is MCs who are some kind of fighter/warrior and/or the “very good at everything” power fantasy types. So playing/reading such HGs or COGs will most likely mean me getting stuck with the kind of MC, outside of maybe female damsel MCs, I want to play the least. If there had been more HGs and COGs with gender-locked male MCs who didn’t fall into those stereotypes, I’d at least take a more positive attitude to that.
But I will also say that I’m, at least when it comes to HGs and COGs, are opposed to gender-locked MCs as a general principle, with the only possible exception being stories that focus so much on a quintessential female or male experience that it’s quite impossible to imagine them with a gender-selectable protagonist. I think it does encourage gender stereotyping too much, like with gender-locked male MCs being reserved for HGs or COGs focusing on warrior/fighter MCs and/or power fantasy MCs and gender-locked female MCs being reserved for damsel or woman in peril-stories(like Donor, from what I understand) or where the MC being the focus of romance is the focus. Even more importantly, it also de facto locks out those who need to at least have the option to play an MC of their own gender, out of those stories, instead of playing to what I think is one of the greatesChoice of Games’s, creating stories that makes readers feel welcome, whatever their gender, sexual orientation, ethnicity etc and gives the space where they can feel that the story is for them, instead of them feeling like observers of someone else’s. story. So as a matter of principle, I would probably be, at the very least, very hard to convince to try even a HG or COG with a gender-locked male who wasn’t necessarily a warrior or good at everything-power fantasy character.
I’d give a bit more of a leeway to HC releases with gender-locked male MCs(but would require it including female ROs), both since there have been so much more HC releases with gender-locke female MCs and since it may be that making sex scenes at the highest levels of spiciness and other aspects of making pure romantic content is significantly more challenging for MCs of both varying genders and sexual orientations than making sexual and romantic scenes in regular HGs and COGs. I’d still need the male MCs to be a non-warrior and non-power fantasy MC for me to be interested, though.