I am curious about why your vintage steel bikes feel uncomfortable to you.
I am guessing it is:
- tight geometry (short chainstays, steep angles), and
- small tire size (do you ride on 23c's or smaller)?
You can replicate those problems in any modern material and end up with a harsh-riding bike.
Or you can fix them with an off-the-shelf carbon bike, or a custom steel or ti bike.
I don't think the frame material matters as much as the geometry of the frame, your fit on the bike, and tire size.