Quinn and Rabo are among the most competitive unit linked funds on a charging basis available in Ireland. In certain circumstances, going through a broker may yield a discount on other funds available.
Rabo may charge more due to the fact that their funds are actively managed, whereas Quinn funds are index trackers. Whether it is worth paying more for active management is a much wider debate.
Even though I am all for low charges, don't invest on this basis alone. Look at what the fund aims to do (e.g. track an index etc.), what the risk profile is etc. and whether all of this suits your needs/goals.