This is a question everyone is asking! :) The people who live in Istanbul says that Istanbul is better and people who live in Izmir say the otherwise. Well as a person who lives in Izmir, I must go with my city. I've been to Istanbul but it's deadly crowded and full of inhospitable people. (sorry not sorry) Izmir is like a coastal city, in here people are born to communicate. :)

Buttt, if you're asking about the historical side, I must definitely go with Istanbul. There are lots of amazing mosques and palacas there, lots of places to visit.

I both live in İstanbul and İzmir. The question that you asked is not clear. As other friends said if you're interested in historical places İstanbul is really better but in İzmir things are different. You can enjoy without being disturbed by crowd. Here is my advice for you if you have a short trip you can choose İzmir. But if you have a long trip go to İstanbul. There are lots of places to visit there

I live in Istanbul, but never been to Izmir, my question is about the Natural sites, the hospitality of the people and the ease of transportation ...... in addition to what concerns me the most which is to know in which city people speak better English !!

I think,İzmir; because İ haven't been to İstanbul :)