For a modern but classically constructed steel frame, I would consider a mixed group with some modern parts where it's important, and more classic parts where it's less important. For example, I would suggest a 10-speed Dura Ace 7800-series drivetrain with 10-spd down tube shifters, but with a classic TA crankset, which should work just fine with any modern 10-spd drivetrain. The current 7900 series looks very modern but the 7800 series is very classic. A TA crankset also allows you to dial in a diverse range of gearing. You mentioned hilly riding. I don't know what type of gearing you need, but I recently built up a modern steel frame (A Rawland Stag, 650B) using the above-mentioned drivetrain (but with 10-spd bar-end shifters) for hilly riding and it's been great.