A couple years ago, I remember someone saying that alternative dice schemes are unnecessary; the only methods of character generation you need are 3d6 in order or just letting the player pick whatever scores they want. I haven't really considered that second option, especially as an option for individual players, but I think you could make this work and still maintain the "adapt to what you're given" feel for all players.
What I'm imagining here is that each player has an option for each ability score: either roll 3d6 and take what you get, or pick whatever score you want, but roll on some kind of random background table, which may give you bonus stuff or annoying drawbacks. This could be a single table, with one roll per 13+ ability score chosen. Or it could be a unique table for each race.
Or it could be a unique table for each ability. Instead of avoiding the 3d6 roll, the player decides whether a 3d6 roll will be applied to a given score, or to the table, with some kind of modification based on the score the player picks. I haven't decided yet what kind of modification this would be, but there are two possibilities:
- Use the bonus/penalty associated with that ability score. If you choose Strength 18 and that gives +3 damage or attack in the rules you are using, then you get a +3 on the background roll instead.
- Add the score itself to the background roll.
With the first method, the background roll table would have entries from 0 to 21. With the second method, the entries would be from 6 to 36, so there would need to be more possible results.