There are a lot of modern composers that uses a lot of structuring on their songs. From movie soundtracks to new age piano, from progressive piano to easy listening. We can hear variations on the same theme and / or crazy free style composing piano, or we can hear other structuring. How is the structure of your perfect song?
For me, I like complex structures formed by many variations on the same theme.
How about you?

I don't think any structure can be perfect without reference to the themes and harmonies. Everything that goes into a piece is interdependent. Having said that I like a variety of thematic ideas and then will vary them in a form that's best described as a hybrid of sonata and variations form. However even that description falls short because what's really important is to not impose a form upon the music but let the music find it's own form. I listen hard for where the music takes me.

I never think about it. If it sounds good to me, then I like it. Structures are probably 4th or 5th on my list of musical criteria when judging music (classical genre). If, on the other hand we're talking about popular music, structure usually plays a bigger role to me because the harmonic and melodic content is usually so meagre (and I mean MEAGRE).

i think structure is definitely not the MOST important thing ever, but it's definitely worth thinking about.
structure further brings out the musical materials you write, and gives your piece a climax.
one of the most important things about structure is that, when you modulate into a contrasting key (usually dominant) in the middle section, and modulate back to home key, it makes the tonic center more obvious and really brings out the tonic-dominant relationship.