Hot take: the Neutral ending is disappointing

Don't get me wrong, I love the the Flowey fight, it's probably my favorite part of the game. But the game railroads you into "betraying" Flowey and choosing to live with Martlet regardless of your choices. Choosing to kill or spare the various enemies you encounter is a pretty minimal form of player expression, but it's still much more story choice than many other RPGs. It's a way of role-playing in this Role-Playing Game. If I want to be vengeful and violent but not to the point of hunting down every last enemy, or want to be a schmuck who trusts Flowey completely, I can feel some of that in the consequences of my actions, but that illusion of choice falls apart at the end where you're railroaded into one choice and Flowey acts like you went out of your way to choose it.

Not only that, but the ending of Flowey automatically resetting is pretty anticlimactic. I expected that since the game didn't have any characters from Undertale playing major roles, any ending could be potentially canon regardless of what you do or who you kill. But nope, it's Pacifist, Flawed Pacifist or nothing.

There are some counterarguments to this. Most obviously, the Flowey fight is extremely high-effort and high-quality, and the devs don't want people to miss it based off of a last-second choice to decline Martlet's offer. This is fair, but an easy work-around could be having Martlet stay on the roof if you decline her offer, letting you reload and go back for the current Neutral ending after you get the "listen to Flowey" Neutral ending.

A better counterargument is that there's no possible satisfying Neutral ending. Dying unavoidably to Asgore with no actual final boss would suck. Asgore pulling a "lose the fight, win in the cutscene" would be annoying since not only is that a frustrating trope, but you'd just be fighting a boss from Undertale with unchanged context after the whole game before avoided retreading things Undertale already covered. And defeating Asgore and getting inevitably backstabbed by Flowey after he absorbs the souls would not only be repeating what happened in Undertale, but would be even less canon than the Genocide route. At least after the Genocide route you can decide that Clover feels guilty and resets. There's current Neutral ending may be disappointing, but any alternatives would be even worse.

Finally, in my opinion the best justification for the current Neutral ending is that it's in character for Clover to want to live with Martlet. All of the other endings have Clover make in-character decisions independent from the player, and it's established that Clover wants a better life between the allusions to their bad home life and them staying with Toriel in timelines where Flowey doesn't interfere. I don't have a rebuttal to this.

So yeah, there are good reasons for the Neutral ending to be the way it is, but it still frustrates me that I don't get to make meaningful choices even in Neutral.