What we have used and found to have a really nice attitude, that you would like to see a very young kid get to be around-- Kadabra, Sunseeker, Jakes Proud Jazz, and most shorthorns, and quite a few of the higher percentage Maines.
We dont really start them young and just kind of halter and go -- after they are weaned. The calves sired by the bulls I mentioned above seem to be calm and like being handled.
Maybe I am getting old, but I am appreciating the calmer and unchallenging calves more than I used to.
Hope this helps and have a good one