Eric5h5 is saying use what you need, textures take a lot of space when building a project so you wan to use the size need and all depends on it's use/need.
um, Is there any solution to make the textures compressed? When I've made the textures compressed it looks blur in my mac. So I had to set it Truecolor. _Masudias
Use PVRTexTool. Unity uses a fast but poor quality option. As for resolution, only obsolete iOS devices were limited to 1024. All the new models from 2009 on have had 2048 as the max.
i thought my problem was the texture size, but the real problem is unity transparent difuse material is lagging my game if i use the material only difuse theres no lag