I do not have Baroness so I cannot say with certainty, however, I have Tayrel which is one of my strongest champs currently. I have built him with (2) speed sets and (1) defense set.
I would prefer (3) speed sets however I had to choose the best gearing option based on what gear was available to me, his current power is just above 28k
Some people say lifesteal and speed, while, others say full speed.
I have noticed he is always side by side with my champs with lifesteal until the end of the fight and typically can outlast them due to the high defense.
I have focused on crit damage gloves, defense % chest, and base speed boots.
substats include speed, defense%, crit, crit dmg, accuracy, hp%, resistance -- somewhere in that order
I use tayrel with this build for everything