I like both.

The second category is hard to do well, but when it is it's glorious

I personally like both a lot, but I have to admit that the latter is kind of overdone nowadays.

If we know that characters are evil from the start - that means they have more screen-time to show villainous charisma i love so much (sadism, aroggance and etc). So yeah - prefer to know character is evil from the start.

It depends on the story and the writing. Twist villains can be done poorly but can also work very well if done correctly.

Twist villains, only with good writing though