Then I'd pick BotW.
Like another poster said, BotW is a once in a lifetime experience, and somehow strikes a kind of beautiful perfection even as, oddly, TotK is mechanically better in most respects.
BotW achieves something unique by dropping you in what's left of Hyrule a century after Hyrule was defeated. And it's a wilderness that could have been desolate, but it's not: it's beautiful. Things are growing back, despite everything. Wildlife, but settlements, also. It's all sparse, this renewal, and there's so much woe yet to fight. But it's there. And the mood is both mournful, and quietly hopeful in a way I find comforting and deeply healthy.
BotW is built around a core of emptiness, but that emptiness is not a void: there are countless secrets and little wonders to unearth everywhere, everywhere. Sometimes it's a treasure, or a trace from the past. Sometimes it's the shapes that rain drops draw on wet moss. There's wonder everywhere, just a wander away. BotK understands this, and elevates the wandering.
Where TotK is full of activities and minigames and quests everywhere, so you're never at a loss for what to do next, and it's by all measures a richer, bigger, fuller game. But it's also, squarely, a lesser experience.
Of the two I'd pick BotW in an eyeblink and it's not even close.
But that's my answer, not yours. Only you know what you're looking for in a video game.
See my answer above for my personal take on this. TotK is a bigger, longer game with far more things to do, but in filling the delicate emptiness that's at the heart of BotW, they also made TotK... mundane. Greater, by most metrics. But mundane.
When I played TotK, I enjoyed myself a lot, then moved on to the next item on my pile.
When I played BotW, I experienced something unique, and it stuck with me since.
EDIT: Folks, maybe don't downvote OP just because you disagree with them? They opened an interesting discussion and I for one am glad for it.