Just use whatever fruit you have in the house - it's always good to try different combinations. And if you can try and get a good rainbow of colours in there so that you get a good range of nutrients.
This is a great way to use up any fruit you have left in the house, maybe from a fruit box you've ordered. Over ripe is better than under for good taste and it wont matter if the fruit's a little soft once it's all chopped up in the bowl.
Bananas, apples and oranges are a good place to start, then try adding something you haven't tried before, maybe mango, pineapple, passion fruit, strawberries, pomegranate or any other fruit that is in season and available to you.
Just drizzle over a little citrus fruit juice to stop the fruit turning brown.
Any why not try serving it with some good quality natural yoghurt and maybe some sesame seeds (you can toast them if you like by frying them for 2 minutes in a dry pan). You could also try squeezing over a dash of lime to give it a bit of a zing!
Even children who say they don't like fruit tend to enjoy a good fruit salad!