Any high quality steel frame and with lugs but the lugs issue is more of a looks thing with me. I also like Titanium but because of no lugs used on these frames they look to industrial for my taste. I feel those are the 2 strongest and longest lasting materials for bikes. Hey, if Sheldon Brown can commute on a steel bike made in 1918 of inferior steel compared with todays high tech steel and not feel he is riding a bike that is going to crumble to dust or break while riding it, then there must be something good about steel.

I wish I could be alive in another 80 years just to see how many current generation carbon fiber and aluminium bikes are still around and ridden daily!!!