One of the recommendation I got when I started playing was: never sacrifice 3* heroes, keep them until you have a good roster.
After keeping 2 TC13 active for several weeks, I have 7 heroes 4*, which build a decent team, and 71 heroes 3*, most of them are 1.1.
I play all modalities: war, titan, map, etc
I don’t know how many heroes to keep and train for each color. I would say 6, so I can do well in war, but maybe more, because I might want to color-stack.
For instance, green, I have:
Little John 4* 3.60
Carver 3.50 +9 talents
Belith 3.50 +7 talents
All the following are 3* untrained: Myggy, 2 x Isshtak, Friar Tuck, 3 x Berden, 3 x Carver, Belith, Brienne
Which of the 1.1 should I sacrifice?