I find Bladesingers to be too powerful for their cost. Going up against Chosen (1450) Bladesingers (1200) it's an even fight mostly from what I've seen. I love Wood Elves but Chosen should really be that hulking scary armoured threat. Chosen are a single focused unit whereas Bladesingers can augment their style by an ability to do more base damage at the cost of AP. The fact that they can do this should probably give them an increase in cost or imo CA should nerf them slightly to keep them tough but not as tough as an elite tier Chaos unit like Chosen.
As a disclaimer Chaos aren't my choice army of playing but I love fighting them. Empire, Wood Elves and High Elves are my thing but I do see that this last DLC like all is giving power creep too much in this regard.