Being primarily a Warriors of Chaos player, it makes me somewhat sad that the competitive choice for a lord in most normal sized games automatically defaults to the sorcerer lord, as they are simply a better use of points given 8th edition rules and the relative weakness (in terms of what it can bring back in points) of the chaos lord. Seeing that Warriors may be up for a new book late this year (hopefully), I thought I would throw out my suggestions to make chaos lords a much more attractive alternative to the sorcerer lord (since with chaos it is unlikely that you will be able to fit both into a normal sized game). In trying to keep with the fluff of chaos lords being destructive masters of combat with little regard for their own lives I have come up with the following:
Chaos Lord (base) - 220 points
added abilities: unbreakable (only applies to the lord himself and is not transferred to the unit he is in (ie they can lose combat and flee, but he remains)), combat lord (for every hit that wounds, the lord gets to make another to hit roll)
Khorne - Heroic Killing Blow (+40 points)
Nurgle - either regeneration OR +1T and +1W (+40 points)
Slaanesh - ASF and +1L (+35 points)
Tzeench - either a 4+ ward save (with no ability to improve it) or level 2 tzeench caster (+45 or 50 points)
I think these changes would make the chaos lords a more playable choice without breaking them entirely in terms of power and would then directly reduce the amount of chaos armies led by sorcerer lords (which I think would be a good thing).