Neither are perfect, but 1) is pretty close, while 2) has incorrect grammar. 1) The more attractive and informative an ad (is), the more effective it is. You need to use the article "an". "Is" is optional. In this case, because you also use "is" at the end of the sentence, it is better to leave it out of the first part. The more attractive and informative an ad, the more effective it is.

Neither is correct, but they could work with minor changes: 1)The more attractive and informative THE ad, the more effective it is. 2) The more attractive and informative the advertisement is, the more effective it is.

Hi there. Actually both sentences are grammatically wrong. Let me rephrase them both and see if you prefer them. Yours: The more attractive and informative ad, the more effective it is. Mine: The more attractive and informative AN ad IS, the more effective it GETS. or Yours: The more attractive and informative is advertisement, the more effective is it. Mine: The more attractive and informative AN advertisement IS, the more effective IT GETS. When you rephrase them correctly, you can see that the sentences are actually almost alike. I would pick the shorter of the two though, as essays tend to have too much filler words. Hope it helps.

The first sentence is better but I would say: The more attractive and informative the ad, the more effective it is.