Really impossible to test the effectiveness of the three head-to-head, as the J&J was tested much later as you mentioned, when we were at the peak of Covid. There were also all of the variants around. J&J also had the most diverse testing population, that not only included the USA, but South America, Mexico, and South Africa. Finally, the J&J's viral vector platform has been around for many years, so there is long term studies on it. It is used in the Ebola virus and even approved for pregnant women and children in Europe. It is also being recommended for the more transient people, whom many times can't get the second shot (or no tracing for them to get the llsecond shot).
Had my J&J yesterday. No side effects at all. No soreness. No sluggishness. Did my standard run and bike ride this morning I ran too but only a few steps. Jk