That's a good point about having some selection. Sunsuper (as I'm sure a lot of the larger funds do) provide a large range of managed funds/ETFs within their portfolio and allow you to allocate yourself. I started out doing this but then re-allocated to a life-cycle fund which automatically changes your risk profile and allocation as you get older.
As for returns, you unless you are a sophisticated investor (and even if you are one), for super you would probably want to go with the index fund strategy of taking a tiny slice of the whole market and take the average market return (with much lower fees). Almost no actively managed fund (with much higher fees) can beat over a long period of time.