You should use a 12 or 24 words seed phrase ?

[satscraper]

Maybe a 24 word seed phrase will however become more relevant in the future when there is more and more computing power available. Is there any calculation if it will be possible to crack 12 word seed phrases with a super computer maybe in the next 50-100 years if you take into consideration how fast the capacity grows?

There will be no ways to crack either 12 or 24  words seed phrases (providing they  are  not biased on some extend)   in any future as such actions  require enormous source of energy.  To avoid repeating comment I head you to the relevant estimations based on Landauer's principle https://bitcointalk.org/index.php?topic=5477971.msg63329443#msg63329443

[riqo]

The number of posible combinations exceeds 2.6 undecillion potential pairings.

What is that weird unit you used? It is not even universal! According to google it is one thing in US standard and another in UK standard and who whos what it means in the rest of the world. Use the universal ways, something like e+36

BTW 2048^12=5.44e+39

You can learn everyday something new, you know now what  the undecillion word stands for 

[nakamura12]

You can learn everyday something new, you know now what  the undecillion word stands for 

We can learn everyday which is true but some people aren't learning right away because some people might be slower when it comes to how fast a person can learn. Anyway, back to the seed phrase where 24 words is much safer but still it is possible to lose money if ever a person is able to know the words then he/she will be able to take it out of the wallet. Losing money is not all about brute force but scammer find a way to steal your wallet seed phrase. It is all up to the owner to keep the wallet safe.

[curiousNoone]

You can learn everyday something new, you know now what  the undecillion word stands for 

We can learn everyday which is true but some people aren't learning right away because some people might be slower when it comes to how fast a person can learn. Anyway, back to the seed phrase where 24 words is much safer but still it is possible to lose money if ever a person is able to know the words then he/she will be able to take it out of the wallet. Losing money is not all about brute force but scammer find a way to steal your wallet seed phrase. It is all up to the owner to keep the wallet safe.

True but like OP posted you can have 24 words and someone know the seed but if the order of words is mixed up then you need some divine intervention to crack it.

[ranochigo]

Anyway, back to the seed phrase where 24 words is much safer but still it is possible to lose money if ever a person is able to know the words then he/she will be able to take it out of the wallet. Losing money is not all about brute force but scammer find a way to steal your wallet seed phrase. It is all up to the owner to keep the wallet safe.

12 words and 24 words have marginal difference in security increment. I wouldn't call it much safer by any regard. 12 words seed phrases are easier to keep than a 24 words seed phrase and hence a better option.