coyote6
Adventurer
I'll go with three: relatively normal (albeit fairly badass) folks, awesome heroes, epic/legendary heroes. Each level, the types of things characters are capable of would change -- e.g., at 1st level, you can individually fight one decent opponent or maybe a couple of mooks & collectively (as a party) take on a larger monster; at 2nd level, you can individually take on a larger monster, or fight groups of ordinary opponents, or collectively fight, say, a dragon; at third level, you can individually fight those tougher monsters, fight masses of minion-types, etc. Each level would be sort of like D&D 4e's tiers, except more explicitly divided & compartmentalized.
Then within each level you could have smaller advancements, too; perhaps call them "character points".
Then one group could play solely at level 1, or levels 1-2; or they could start at level 2 & work their way up to 3; or if they wanted to be Exalted, they could start at level 3.
That would be awesome.
Oh, and then you could make the basic combat system be gritty and somewhat harsh (it would depend on detail, but limbs could be hacked off, etc.), and then provide some other resource-based system that would allow more cinematic play -- an ablative pool of points that would be spent (automatically or by player choice) to completely avoid the horribly gritty effects of the base system. Then, when you were out of these "avoid being hit points", you would be in trouble. There might be tiers, where individual campaigns could decide how many of these points PCs would have -- e.g., None, Low, Medium, High, or whatever.
Then within each level you could have smaller advancements, too; perhaps call them "character points".

Then one group could play solely at level 1, or levels 1-2; or they could start at level 2 & work their way up to 3; or if they wanted to be Exalted, they could start at level 3.
That would be awesome.
Oh, and then you could make the basic combat system be gritty and somewhat harsh (it would depend on detail, but limbs could be hacked off, etc.), and then provide some other resource-based system that would allow more cinematic play -- an ablative pool of points that would be spent (automatically or by player choice) to completely avoid the horribly gritty effects of the base system. Then, when you were out of these "avoid being hit points", you would be in trouble. There might be tiers, where individual campaigns could decide how many of these points PCs would have -- e.g., None, Low, Medium, High, or whatever.