I can't really stay productive on anything less than 15". Right now I'm currently enjoying this years lineup of 17" laptops whose body is basically what a 15" was some years ago. I do graphics and sound production aside from programming so I'm really enjoying the extreme screen-to-body ratios. Vapor chamber cooling is also a nice addition.
But the thing that really gets me is the 16:10 resolution, I could personally never go back after using it, it just feels correct (to me).