So far it looks like D&D will win, likely 3.5. For D&D 3.5 I have 3 potential campaign ideas.

Campaign 1: With this one you will play a monster of some kind, you can pick any race or monster that is at least vaguely humanoid regardless of LA or racial hit die as well as a class. With this one you will work out with me what you get from your race at each racial level. You can choose to take a level from any class you have access to or from your race every time you level up, as to what classes you will have access to. At the campaign's start you will only have the Player's Handbook but throughout the campaign you will in character acquire different books to take feats, classes, or anything else from. Your character will be vagualy aware of their stats, skills, etc, if they have an intelligence near average.

Campaign 2: This will be kind of a reverse of most settings, in this the epic battle against evil that happened a thousand years ago in most setting went the other way with evil defeating good. Also, the battle happened a little over a hundred years ago so long lived races still remember it well. One thing the average person noticed was that quite frankly a lawful evil overlord generally does not differ much from a lawful good one in practice. The only remaining good aligned nation as well is in the deep southern deserts, a city-state under the domain of a council of paladins who will maintain lawful good at the cost of anything else. This is a sandbox campaign.

Campaign 3: 50 years ago a new continent was discovered, naturally all the great kingdoms set out to colonize it. There they found new and horrifying monsters, vast trackless forests and jungles, and mountains so high the clouds cut off the peaks that yet no man has survived the climb of, and yet they also found riches. Vast seemingly impossible riches have been found by the rare few in this new land and for those brave few who now live there several colonies now exist for those adventuring deep into this new land. This campaign will have dinosaurs.