Good point Marcus ... though I have to say, (hypothetical) acceptance of the possibility that "B is better in bed," kind of shifts the unique snowflake paradigm to a wider range of traits and activities. So maybe Quin's strong point is heavy conversations that extend into the wee hours, or maybe his strong point is throwing a great party, or taking T out to have some fun on the town, or cooking a wicked meal, or working magic on the car, or creating a relaxed and happy setting at home with a movie and popcorn ... or whatever. In each of those cases, we're still saying, "Well maybe B is especially good at one thing (sex), whereas Quin is especially good at other things (besides sex)." What happens if we discover that B is "The Best" at *everything?* Not that such a discovery would be likely, just asking for the sake of the question's hypothetical value.
So then I think that the most important point is, it's often not healthy to compare ourselves with "the other guy" at all, but rather, that we set personal goals based on our own personal performance as we perceive it. And since the topic at hand is, "How well do we do at showing T a good time," then it must also be important to ask T what she enjoys the most and what (if anything) she'd like to see more of.
It's complicated because people are such multifaceted packages of talents and virtues. If B turned out to be "2nd place in bed," that wouldn't mean T wouldn't still want sex with B. I think she'd still want it because it's still unique and it's still him. T doesn't just want "two lovers;" she wants two men -- two complete individuals (just as they are). I think that makes sense ...
Love means never having to say, "Put down that meat cleaver!"