I think splitting it 4 ways would be best just so people are encouraged that there will be more winners instead of just giving it all to one person. Thanks for doing a giveaway though!
i feel it should be 4 winners, separated throughout the thread ( if your doing post-number winners)
100 million bells is a lot for one person and also will take ages to transfer.
That would be epic! Maybe split up the 4 winners into different amounts >:] 50m, 25m, 15m, 10m or something. Makes it more interesting and 10m is still a good amount