If you want a control surface for Sonar, consider a multi-touch screen. It will integrate better than just about any hardware controller because it needs no driver to interact with the DAW and no configuration in the DAW it just works for a DAW like for all other applications. And it is much less likely to be rendered redundant by operating system updates or you deciding to change software.
For an interface, if the budget allows get an RME UFX+, or for less money a Focusrite or Motu interface with the number of inputs you need. If the interface hasn't enough inputs (e.g. you actually need 32 inputs, most outside pro studios don't) use ADAT to add further banks of inputs. RME interfaces for example come with Totalmix which is a "virtual digital mixer" which removes the need for a physical hardware desk.
What is not needed any more is a big mixer with one input per track each feeding a track on a tape recorder or DAW used as a tape recorder, so long as you're not recording entire bands at a time. If you are recording entire bands many low-price mixers with a USB output actually only send a stereo pair to the DAW down the USB cable, not 32, 24, whatever individual channels.
DAWs can (mostly) have as many tracks as your PC can handle, and you can route any interface input or output to any channel.
If you really want or need to go down the "looks impressive, big digital mixer, maximum hardware, high quality, etc" road then as well as Behringer take a look at Solid State Logic's desks. But be aware you can have all that control in software for a lot less money. Regarding a DAW as a substitute 24 track tape machine while doing everything by routing in and out of a hardware mixer is to miss out on most of what a DAW can do and tape can't.