There always will be a debate whether an active managed fund is better than a passive or non managed fund. A non managed fund, like Barclays iUnits exchange traded funds, are funds in which the stocks and titles which constitute it are not sold on under performance. ETF's follow the indices of the stock market. An active managed fund, like Jarislowsky's funds generally perform above the indicies and actively sell and buy stocks and titles which are included in the fund.
In these questions, the main thing is to do better than the current inflation rate, which is at 3%. If the tsx index did 12 % last year, inflation was 3%, and the Management Expense Ratio was 0.45%, the net gain was 8.75%. If the fund is actively managed, MER are a lot more, between 2.4%-2.8%. The important thing is to do consistently better than the index. And remember past gains are not a guarantee of future gains.
I think the important thing to remember is to always think about diversification in your portfolio. This way, you can always reap the benefits of both strategies.