You already know my answer lol. As much as I appreciate the combat of Elden Ring, nothing compares to the freedom in movement options and places to go in Tears of the Kingdom.

Edit— For those who are struggling with this comparison, the underlying idea is this: Two games which are generally considered the pinnacle of open world gaming, but take completely different approaches. Think of it as comparison Mario Odyssey to Mario Galaxy, or DKBananza to Astro Bot.

Oh boy, this is going to be the interesting

I guess the most important clarifying question is “which did WHAT better?”. I mean, both games are masterpieces in my mind, but they’re attacking different problems and priorities. From the OP, I’m guessing it’s about open world/sandbox design. In that case, I think Tears is better, because of all the opportunities for experimentation and emergent gameplay. Elden Ring is essentially Dark Souls 4 in an open world — which is great, don’t get me wrong — but that means it plays by conventional rules. Tears, conversely, is all about breaking down boundaries — mechanical, chemical, structural, spatial, etc.

I think they both did it really really well.

Not even a contest, elden ring.

They're better at different things. ToTK is a open-world sandbox action-adventure game. Elden Ring is a combat-focused open-world Action RPG. 

This.  I mean Elden smokes TotK in combat, not even close.  The battle system is far superior, and the boss fights are so much better, not a contest.  

TotK smokes Elden in exploration, tinkering and discoveries.  Elden is a semi open world game, I mean technically the player can explore, but good luck running around areas before leveling the character and weapons.    

These are two vastly different games.  

While TOTK is a very good TLOZ entry, Elden Ring is to me the pinnacle of its own genre. So to me this is not even a contest, Elden Ring.

Based on personal enjoyment alone that is, cause given how very diferent these 2 products are, as some people in this thread have mentioned, the comparison is odd. 

TOTK is the greatest achievement in game mechanics in recent years. Moreover, it will likely become one of the most copied examples in terms of open-world design.

The biggest flaw with BotW and TotK, I loved them both, is the battle system. I mean it is kind of trash.

Edit

My dream is BotW exploration, Elden combat and Skyward's dungeons...  

Although Elden Ring doesn't have the same mobility for exploration as Zelda, the sense of reward is much greater in Elden Ring because we're always finding something new: enemies, items, mysterious NPCs. In my almost 200 hours of Zelda, I rarely felt challenged and rewarded, and for me, that took away the sense of adventure and made exploration boring.