here's my opinions:
1. litestep is resource-friendly and very customizable, but to get the max out of it you have to understand the scripting language.
resource friendliness: 8/10
user interface: (1..10)/10 (depends on how you customize it)
friendliness in configuration: 4/10
2. sharpe looks good and friendly, and is customizable too, not as much as litestep though. but unfortunately it's not so resource friendly.
resource friendliness: 4/10
user interface: 9/10
friendliness in configuration: 8/10
3. emerge desktop is very resource friendly and customizable, and you can also use any other .exe (even explorer) as a part of emerge desktop.
resource friendliness: 9/10
user interface: (7..8 )/10
friendliness in configuration: 7/10
sorry for bad english