In my opinion Biomutant is better than breath of the wild...

Breath of the wilds content:
The legendary master sword (which breaks)
Korok Seed Puzzles Scattered about
Shrines (Single trials basically)
Shrine Aperatuses (Trials but always with some motion control BS no one asked for, even if you disable motion controls)
Epic cool looking weapons like the falchion, which break.
The legendary Hylian shield, which breaks after 16 guardian direct hits without parrying.
Flurry Rush which only is activated upon dodging an enemy attack successfully and is very picky about what counts as a dodge.
Side quests which mostly are for 100 rupees or in some cases Fallen Stars (Which are an major ingredient in powering up late game armor)
Cold biomes which require layers of clothing based on how cold it is or you take damage immediately.
Hot biomes which require again, layers of clothing or you immediately take damage.
An biome that immediately sets you and any wooden gear you have on fire upon entering; (The eldin province)
An upgrade DLC to the master sword which "returns it to full splendor" but it can still break despite that fact.
An motorcycle which has no lore behind it, just a motorcycle.
Rupees are mainly used to restock on items and don't appear from cutting normal grass any more, forcing the player to actively seek out ore deposits.
Pitiable jumping mechanic.

Biomutant:
A double jump ability that can cover some distance.
You craft your own weapons from recycled materials.
Dodge rolling slows time and allows you to fire your ranged weapons faster
Re-modification of any weapons you made to make them even more effective
Legendary weapons with unique effects like "Overflow" which ups the capacity by %50, or "automatic" which makes things like guns have better fire rate and become full auto, or "precision" which makes them precise as possible despite what the accuracy says.
Ranged weapons have infinite ammo but must be reloaded, be smart about reloading and you don't need to wait as long for them to recharge.
Interesting brain teasing mathematical puzzles are dotted throughout the map, such as pre-apocalyptic:
- Telephone booths
- TVs
- Projectors with hidden lore about the biomes
- Toilet pipelines (Yes, I'm serious)
- Microwaves
- Globes
- And even electrical panels that'll test your strategic knowledge: XXYYZZ, orange to orange / white to white, etc.
- and if you complete a puzzle you get gear from it, with the final puzzle giving you a special gear set themed to that puzzle, you also can't just brute force a puzzle cause it has a limited number of moves.
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Vaults which contain unique gear, how do you access vaults? Find a monster nest, track down the monster, skin it for valuables and you'll get a key that was lodged in its stomach.
Unique biomes, each with a unique threat:
Heat: Biomes that are literally on fire, you need biological resistance upped with a bio crystal or clothing to mitigate getting through these areas.
Cold: Chilly Biomes, wear warm clothing or up your biological resistance with a bio crystal.
Radioactive: Biomes that can make the character get stunned and suffer migraines, bio crystal biological resistance or clothing needed.
Biohazard: Can stun you by making you throw up. Biomes where you can get more biohazard crystals, modify your characters appearance, and of course need biological resistance or clothing to mitigate it.
Hypoxia: The only biome where you CANNOT get biological resistance to, only clothing can mitigate these oxygen-deprived, polluted zones, these are also some of the hugest biomes in the game.
Oil: Puddles of oil slowly sink the player and can lead to instant death if you can't get out, oil can also disable jumping.

Also, unlike breath of the wild, each biome will warn you you're entering it on the top right saying something like [BIOHAZARD WARNING: %12], and then at fifty percent start giving you constant damage, and at 100 percent will receive considerable amounts of constant damage.

Sidequests that actually reward you with unique vehicles and mounts that make biomes or travelling so much easier; you can even go on foot and delve for upgrades if you want to make your vehicles better right away.
A water motorcycle with lots of appearance customization, and a mount that requires a lot of work to surpass that vehicle.
An mech which can only be activated in Hypoxia zones; if you find more pieces for it? It even is providing you oxygen when mounted.
An bat mount which glides for an huge amount of time which I recommend over the generic glider.
Ziplines and climbing spots outlined in yellow paint.
Sidequests actually reward you with more content, more options, more ways to spend your in-game cash (which is called "green", which is recycled plant matter), want to change your fur style? There's a barber.
Want an overpowered healing item? There's an drink distributor; which sells 2 very powerful healing items every 24 hours that can be restocked.

And man, the optimization in biomutant? It's magnificent. It's like the graphics of The Last Of us 2, Sly 4, and an PS5 hard drive had a baby made of pure gold: And it runs as smooth as silk on any gaming PC, I tested it on my 1,000 TB PC which would run anything smooth, then I tested it on an older, 1.4 TB PC; It still ran smooth, no hiccups even after leaving the game on for 24 hours.

In many ways, Biomutant is what Breath Of The Wild tried to be, and Biomutant is the better experience for that reason.