Continuing with the Bard, which I will compare with the Warlord.
Defense and basic offense are the same.
The Majestic Word of the Bard is clearly better than the Inspiring Word of the Warlord.
At 6th level, the Warlord is healing 6 points per character per action point, which with 4 allies is about 12 points per combat. The bard is granting 4 temp hit points per round in which a foe was bloodied or defeated, which is probably quite common. These abilities seem at least somewhat similar.
The bard has a high Con, an especially useful secondary statistic due to the healing surges. But the bard has to buy Melee Training in order to have effective basic attacks.
The warlord has Combat Leader, a strong ability. But the Bard has Words of Friendship, an extra skill, skill versatility, and bardic training, which I think is plenty of compensation.
The bard gets multiclass versatility, and a lot of those multiclass feats are pretty good.
The bard can choose to mix melee and ranged at his leisure, but he has no effective ranged basic attack. The warlord can throw only basic javelins as his ranged attack. I think the bard is better here.
So far, due to his horde of class features, it seems clear that the bard stands ahead of the warlord. Those PHB2 classes have a lot of cool class features!
Both classes have a pleasant selection of at-will, encounter, utility, and daily powers. The warlord appears to have an edge if you cherry-pick the very best powers – none of the bard powers strike me as being as far above average as warlord superpowers like Bastion of Defense and Stand Tough.
My analysis only covers low levels, which is what I tend to be most interested in.
So it seems like the comparison is what I’m seeing as typical between PHB1 and PHB2. The PHB2 class has better class features, but a more balanced selection of powers. If you assume a random choice of powers, the bard looks rather better. But if you minimax the power choices, the warlord catches up, potentially even passing the bard (it is hard to compare big dailies with reliable powers).