Restaurant chains in Poland (Warsaw)

Hi there, we are an international franchise of Spanish restaurants. I am currently evaluating the potential for our concept in different towns over the Polish geography. Is there any restaurant chain that comes to your mind as a good example of strong, good quality restaurants appealing to middle and middle high income individuals, which I could use in order to do a little bit of benchmarking. It does not have to be Spanish or "ethnic", just a nice place where you like to go.

Thanks for your help!