Because they are the most entertaining and most enjoyable characters.How are they the best of their generation when they failed at everything?
Ashura was the one who became the successor,madara lost to hashi,minato became hokage,when kushina was giving birth mikoto told her I can't believe someone strong like u is actually scared of something,itachi and minato aren't from the same generation
Sasuke lost to Naruto
It's too soon to form an opinion on sarada and boruto
With exception of a few, the non Uchihas are usually boring.