The aggregator question splits UK operators sharply, usually along the lines of how much of their volume already comes through one.
The honest answer is that both models make sense at different points, and the mistake is choosing without doing the arithmetic on your own numbers.
Discovery. A guest who has never heard of you finds you because they were browsing for dinner. For a new site with no local reputation, that is real value and hard to replicate.
They also handle the delivery operation, which is not trivial and not free to run yourself.
Commission is charged on every order, permanently, and scales with your success. The commission on your thousandth order is the same rate as the first, long after the discovery value has been delivered.
The second cost is less visible: the customer is theirs. You do not get the contact details, the order history, or the ability to bring that guest back directly. Every repeat order pays the commission again — you are renting a customer you already acquired.
Direct ordering is a fixed monthly cost regardless of volume. So the two models cross at a specific point for your business, determined by your order volume and your commission rate.
Below that point aggregators are cheaper. Above it, every additional order on an aggregator costs you money a direct channel would have kept. Most operators have never worked out where their own crossover sits.
Both, deliberately. Use aggregators for discovery and accept the commission as an acquisition cost. Then work actively to move repeat customers onto your direct channel, where the margin and the relationship are yours.
What does not work is drifting into full aggregator dependence without noticing, and then discovering you have no direct channel and no customer list when the commission rate changes.
Calculate your crossover point using last quarter's actual orders. Put your direct ordering link on everything that goes out of the kitchen. And capture guest details on direct orders from day one, because that list is the asset the aggregator relationship never builds.