I voted steel because my old spinal injuries can't handle anything stiffer (and I can't afford high quality carbon or ti),and it's all I own anymore...save for that Wallycruiser (Walmart 26" cruiser),it's aliminum but rides like steel.

Technically I don't "commute" though,I explore\joy ride\utility ride,since I'm "disabled" according to the US gov now-a-days.