Speedy, because you can quickly understand that you aren't skilled enough to work with the prop trading firm;DD
Just a joke.
But actually, yeah, I myself opted for speedy challenge and passed through in the blink of an eye. Conditions are interesting, those imposed requirements to comply aren't high, so even if you aren't a seasoned trader, just an intermediate one, you can pass through it.

Better in what sense!? In terms of the time required to pass the assessment and start trading with a funded account, then it is definitely the Speedy option. This is created for those willing to start trading earlier, those who are confident in their skills, and those who are already comfortable trading with such rules. In other words, this is for those more advanced traders.
If it is your first time trading with a prop firm, then I recommend you to take it easy and go with the classic assessment.
It is beneficial for you to spend more time trading and practising the discipline required by the rules. Being disciplined in your trading is of utmost importance. And we all know that to gain discipline, all you need to do is practise.