Actually very low amount of people show this jutsu.
For example, the only current kage who used a summon, is tsunade.
Summoning technique seems quite powerful.

1 Which characters(that have not shown a summmon) would you like to see with one?
2 What kind of summon would they have?
3 Which summon would you like to have?

1 Konohamaru.
2 Monkey's.
3 Cats.