As of a few years ago, I had an aluminum hybrid bike that was awful. It was joyless and dull to ride and for about a decade I thought I just hated bicycling. And then I had a series of epiphanies that led to me buying a 1982 Bianchi road bike. It was zippy and just wanted to go fast. In a single summer, I went from not having biked more than a few blocks in years to riding a century. So that was my experience in 2018: aluminum = joyless, steel = joyful. Last year I decided that I wanted a bicycle more suited to the riding I wanted to do. The Bianchi was designed for racing and it was a little too small for me anyway. So I looked and I eventually settled on an aluminum Cannondale Synapse 105, and I LOVE it. Cannondale makes a big deal about it's "SAVE" frame architecture that builds some resilience into the frame. Whatever it is, it does not feel anything like the aluminum hybrid bike I used to own. Perhaps I would have preferred the CF, but the aluminum version was about as much money as I'm willing to spend on a bike. I have kids to put through college. Anyway, yeah. I'm a fan. If properly designed, aluminum bikes are an affordable and even elegant material for bicycle frames.