AS mentioned already, the differences in quality of steel is massive, infact, biblical.
A gaspipe/low end (old or new) is going to suck no matter who builds it. But some proper steel will see you right.
For me I like a road bike/racer to be either decent steel or decent carbon, I find aluminium generally much harsher on lower back.
Also consider putting a carbon fork in there, handbuilt quality steel forks are often as much as the frame! vs. an off the shelf high end carbon fork will likely handle better/torsionally stiffer + absorb more shock/vibration than any steel or alu fork would = more comfort, more control and ultimately lower weight (if thats important to you).
Weight can be a factor, but my 40yr old bob jackson build (equiv of ultegra group + 27" 32c touring wheels) with modern pedals weighs just under the 10kg mark, and would be about 8.5kg with similar age sprint wheels on, which yeah its comparable to a low/mid range alu framed current gen racer, but it won't be as stiff for the same weight.