seem like you need a van for that pax and luggage

didi from what i heard people say is cheap...how cheap i don't know
but i think what you should worry about is how to take didi or e-hailing at airport...the way they take e-hailing at airport is different
i think you should search video on tiktok showing how...where to go, what to ask the driver(ask for number)...if not you'll be confusing AF
better if you know how to speak chinese if not the driver will keep calling you and u don't know what to answer

All depends on what you prioritize for your party. And also what you have prepared for the trip.

DiDi is very affordable and you have to order one capable to fit all of you & luggage (or 2 Didis). Didi driver will likely call you when he can't find you among the crowd and if you do not have a local number, may incur some inconveniences.

Most hassle free would be to take airport transfer, but likely most expensive.

Most economical would be take the Metro, if your accomodation is near a station. Also depends on your parents fitness and walkability.

Hope it helps you to decide, but sorry for not a straight forward answer.

Trip has the option to have the driver holding a card at arrival gate.  Select that. With parents, I would opt for this option.