YOP Poll Plugin is smart, small (fitting in side bar gadgets column), with attractive layout and allow to define almost everything in background. Couple of predefined templates (with ability to change them manually), clearly described features and options let users easily understand how to use and configure whole stuff. It's exactly what I was looking for.
The only thing missing for now (version 1.5) is graphical presentation (bars for example) of voting results. But I believe it will be implemented in the future by YOP team :)