It's really a matter of personal preference, along with the alignment of equipment, operational parameters and barista skill (and patience).
Personal preference: are you a fan of any cafe's espresso? This is the quickest way to find an espresso to work with. (it helps to learn to taste straight espresso, to cut through any "spicing up" or "grooming" an espresso-plus-adulterants beverage may require... if you're a fan of steamed milk with your espresso, try the smallest milk-plus-espresso drink possible, to really get a picture of the coffee that's not watered down)
Alignment of equipment: Does the tamper fit in the portafilter basket perfectly? Can your machine accept a full dose? Is your group head absolutely clean? Sharp, clean grinder burrs? (only a clean, well-maintained burr grinder will make good espresso possible). Parameters: temperature/pressure settings appropriate for the roast level of coffee?
Barista Skill: definitely worth the investment if one loves the taste of espresso. Just like with any craft/skill, it requires practice and a critical approach.
"espresso roast" can be a controversial term, as any coffee brewed through an espresso machine is espresso. Whether it's a good espresso or not is a different story... many different roast profiles work as espresso, so the term "espresso roast" easily loses meaning.