My stock response to assertions that eating meat is cruel: plants feel too. Many species are self-aware every bit as much as animals are. It’s only because wheat and corn don’t have big googly eyes that we feel no sympathy for them. Implicit in the act of consumption is the notion that our lives are worth more than the lives of whatever we eat.
Even if it's true that plants feel and suffer, the pipeline of plants -> livestock -> food still kills many (an order of magnitude at least) more plants than the direct pipeline of plants -> food, so eating animals still causes more overall suffering.
In that sense, it seems to me that a plant-based diet is still the preferable choice if one wants to reduce unnecessary suffering.
It's an admittedly fun argument, but it has flaws that I think make it unsuitable as a strategy for destroying vegetarians with facts and logic. It relies on abstract, black-box constructions of notions like sensation, awareness or intelligence based on analogy and observation, whereas in animals we can also rely on arguments based on equivalent biological structures. The breadth of that construction also has some intriguing but pretty challenging implications: you might also need to accept sentient traffic jams and Kubernetes clusters that feel pain.
Beyond all that, though, I think the major flaw in your reasoning is it treats concepts like awareness or moral worth as binaries, with language like "every bit as much" and "only because". Of course, one reason we don't treat wheat with empathy or offer it moral equivalence is because wheat doesn't look like us, but that's far from the only reason. Wheat is simply a less complex form of life than a fly, and certainly less complex than Google Chrome, neither of which I feel much compunction about killing when they are consuming my resources.
If you're going to accept an incredibly broad definition of awareness, then that definition also needs to be nuanced and gradated or else you end up saying nothing only with more words. You can absolutely define feeling such that grass can feel, but if that's also "every bit as much" as what humans feel then you've arrived at a notion of feeling that's almost tautological and struggles to support any meaningful consequences. We and the grass are also carbon, I suppose... or energy? I'm not sure why it matters. I care about the version of feeling that made me cry at the end of Homeward Bound, and plants don't have that, no matter what you call it.
All these contradictions disappear if you're willing to say that different forms of life have different levels of awareness, and different degrees of moral worth. Intuitively, I care less about the death of an animal than the death of a person, and I care less about the death of a plant than an animal. That exact mapping from being to moral worth is going to be pretty tricky to define, but I think it's pretty hard to argue that animals should have none at all.
If animals have non-zero moral worth, then there is some area between the curves of your enjoyment and their suffering within which it is okay to eat them, and outside of which it isn't. I don't have any desire to tell you what your curves should be, but as a matter of my own observation, I haven't found vegetarian food in general less enjoyable than food with meat in it. There are exceptions, of course, and I still eat meat sometimes, but as a practical matter I found the exchange rate from dining enjoyment to animal wellbeing very favourable. You might too.
