In Tier 1 markets (big metro areas, in the US), aggregate platforms are the way to go. The main driver of this is liability insurance and worker's comps.
There is also pressure from municipality laws on how delivery staff are titled: if they're delivery then you can subsidize their hourly rate w/ tips but they cannot perform more than 20% of their work as a regular employee (stocking, packing food, etc.)
2nd Tier markets (suburbia) have their own issues and intricacies since delivery is driven and liability insurance become a bigger issue + range. However, they haven't been as aggressive to move over to 3rd party delivery (unless we're talking large corp.)
what in your experience is better option for delivery ... delivery by the restaurant or the delivery by the aggregator platform ...
The first is already there and we are planning to bring the latter one also to the software !