When I built up my LHT I put Cannondale Fire 44cm drops on which are aluminum. I liked the width since they provide a lot of flat space but over the course of my tour I found the drops don't curve back far enough for me.
I didn't have any problems with the aluminum aspect but will be looking for new bars over this summer so this thread should be good to keep an eye on. I'd say try as many bars as you can before you settle on one because that will be the best way to determine what you like the best.