My $0.02:
I much prefer the Unearthed Arcana bloodline approach to the various aasimar/tiefling/genasi races. There are three big reasons for this:
1) You can apply the bloodline to ANY race. Why do all the outsiders just get busy with humans? Earth-blooded dwarves make too much sense NOT to have.
2) The bloodline can vary in intesity. Most bloodlines have intermediate strength, and the big ones have major strength. The blood can run thicker in some than in others.
3) Bloodlines are paid for, and benefits recieved, as the character levels. I like this, because it lets you have an exotic character in a 1st level game.