single texture atlas or multiple textures?

Hi,

I already searched the unity answers and googled my problem but I couldn't find the answer to my current question.

So in my project for iOS I need to have city with all kind of buildings and roads. So to optimize the performance I created a texture atlas as I this is supposed to be optimal for the performance. So know I have all my textures in a single atlas, which makes me face the next problem as I loose the option of using tyling when using a texture atlas. So I have to seperate my buildings in order to assign the objects to their height. This increases my triangle count (about the 3-4 times of what I used before). So I am wondering if this is really the good way to increase performance as I think that the high number of triangles will decrease the performance more then the single texture increases the performance.

Maybe one last aspect. I have about 110 textures in my texture atlas which has 4096x4096 pixels and the city has about 40.000 triangles if I use multiple textures, and about 150.000-160.000 if I use 1 texture. And I use Unity Basic + iPhone Basic + Android Basic. It would be great if someone could give me some advice :)

Best regards,

Fred