Generally, the top of the line race frames, with as low a head tube as available. Fr'instance, Trek riders use 7-series Madones in H1. Cannondale riders used SuperSixes. Specialized riders use S-Works Tarmacs and Venges. Some of those guys get special builds, which generally means longer top tubes and shorter head tubes. Often, the rider can choose between the sponsor's "aero" and lightweight or general purpose bikes (Venge vs. Tarmac, Scott Foil vs. Addict, etc.)
For cobbled classics, many sponsors provide "endurance" frames, but these are generally special builds having longer top tubes and shorter head tubes. The Trek Domane "Classics Edition" is an example, perhaps the only one, of a true race "endurance" build that is in a catalog. Race versions of the Specialized Roubaix might be available if you know a dealer who will contact his district rep for you. Scott-sponsored teams get a special long-and-low Solace, and Cannondale teams get a special long-and-low Synapse. Giant riders get a Defy with a cockpit geometry similar to the TCR or Propel.
It's interesting that the front end geometry of the race Domane, steeper head tube and longer fork offset, flies opposite of Trek's general long-trail philosophy shown by Madones and civilian Domanes.
I have questions. What did you mean by fr? Where are the top tube and head tube on the bike? What is cobbled classics? Why does the size of the tubes determine if it's for endur or sport? What goes faster?
Sport, or race bike are lower at the front, seats are higher, and bikes often shorter and overall lighter. These are faster since the rider is lower and out of the wind, but are also uncomfortable for many more casual riders.
Endurance bikes are a little taller in the front so the rider is slightly more upright, and typically longer so they are more stable. Since the rider is more upright and in more of an aerodynamic drag, those bikes are typically slower.
A strong, faster rider will be fast on just about any road bike, while a slower, weaker rider will be slow no matter how much money they spend on gear. It's 96.875% rider, and 3.125% equipment, but at the top level, that 3.125% can be worth millions
I see from your other posts that you're 17 years old, and ride a Madone 4.5. That's more of a race-geo bike, although with the H2 fit, it's somewhat less aggressive in design than some others. How are your long rides now? Your lower back OK after, say, 50 miles?
I'm 60. I used to own a Madone 5.2 with H2 fit. I owned it for about 5 months before a careless driver totaled it. I did 6 rides over 100 miles on it, and more 50+ rides on it than I remember, and it was very comfortable. A lot more comfortable than the old steel tank of a Schwinn touring bike that I'm now stuck with, until the spring.
You have a very good bike now. Ride it and enjoy it.