I sometimes see teens type:
Instead of typing:
What can you say about it?
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They are equal. Neither is preferable. It is your choice, depending on which you like. A professional, like a speechwriter, might have a stronger preference based on more complex criteria, but for most people, there is no difference.
If you are feeling particularly bold, you might try
Which is a contraction of "I have not". That one isn't "accepted", but most native speakers will understand the meaning, and some accents pronounce "I have not" close to "I've'nt".