Mikuru aswell as VBaal are both limited, so it is kinda hard to bring those into a discussion for the average joe. Also, in that regard, you could choose VBaal over Mikuru and have more then just some BG and Heals.

VBaal needs some support but as soon as she gets it, she can speed your team up aswell as offer some protection. For the Mid-Tier player she is in most cases an actual improvement and in some combinations actually quite good.