If you are car camping, I'd suggest a big burner propane stove too. If you are backpacking, then I'd suggest a Whisperlite. I use two of them when I take groups out about that size. I like that the fuel is cheap compared to a dozen canisters and I like the fact that a large pot sits nicely on the burners.
Good grief... 25 person dinner is a serious cooking attempt for just one person to take care of! Good luck.