Which one you consider the best skill? Writing or Speaking.

It's very close.

Someone can write a good speech, but a talented speaker can make it a great speech.

Superb writing skills have created great films. 

If I had to choose one it would be Speech.  There is nothing greater than listening to someone who can speak well, has good vocal tones and have you hanging onto their every word.

write better because if at any time we forget to be seen again

Speaking is very good as compare to writing. In writing you have enough time to show you best abilities and you can answer in a proper time. but in speaking you have to contact one directly and its more impressive than writing. 

 Hello Mr. Farid,

Definitely speaking as it is a direct communication method. Writing skills are important but not much as compared to speaking. The person speaking is actually processing his/her thought in real time unlike in writing skills where drafts and reviews are involved. The tone, gestures, body language and expression he or she uses support his words hence a much detail message can be conveyed.

In case of a representation of a firm, company or industry, in person contact can be much more efficient. That is why meeting are considered a better channel to discuss rather than sending/receiving mails.

Hope that helps

Regards,

Aziz