For dining, what is the best way to go actually depends on doing the math applicable to your particular situation. You have the DVC card meal discounts at many places, typically 10%, but more in some places, that exclude alcohol drinks. You have the TIW card with a 20% discount, including alcohol, applicable almost everywhere at WDW, which card is actually good for anywhere from 13 to 14 months -- you get an expiration date that is the last date of the month after the month in which you buy the card, e.g., buy any time from Dec 1 to Dec 31, 2020, and it will expire Jan 31, 2022.
And you also have the option of the Disney dining plan. That plan that you can get through DVC is not technically a discount from the one offered by Disney generally, but sometimes actually costs a little less simply because the date its price changes for DVC when there is an increase may be after the price change for the regular guest Disney dining plan. How good the dining plan actually works for your group can vary from being an overall discount from regular food prices to actually being more expensive depending on how you use it, e.g., if you eat only twice day at WDW, you may spend more on the dining plan than if you just paid regular meal prices.
The one thing you do not have with any of the above is some special privilege, such as though DVC, to make reservations sooner than others. My guess for your probable every two-year schedule is that the DVC card dining discounts may be the best choice, but to actually determine which is best requires each member to do the math concerning number of persons in your group and likely eating patterns.
