Bitcoin core isnt better per se, just older and more tested/verified in the real world. I also believe hardware companies like bitbox and trezor have good quality randomness as well.
The difficulty of randomness is a theory(like much of mathematics and cryptography) but in practice satoshi's has had held true since 2009 since there hasn't been examples of collisions or addresses exposed by software using Satoshi's design. Hardware wallets all use unique designs, but borrow from Satoshi's contributions.
You could also roll or flip your own entropy (randomness) with dice or coin, but it's up to you which one you think is best.
