Choosing a PI for my MS/PhD degree in EE based on the h-index?
The only apparent difference between the two being h-index means you don't know enough about these two PIs. Work habits, advising styles, perspectives on the roles of their students...all of these matter.

With that out of the way, lets pretend they are, actually, identical.

The h-index is still a bad choice. There are a few reasons why:


Past performance is no guarantee of future results.
The h-index is something that can be, and is, gamed. But just being "good" at said game does not actually ensure that you are good as an academic, or as an advisor.
The h-index has no context. Are the highly cited articles commentaries with no students on them? If so, they will be of no value to you.


You need to do more investigation. At the very least you need to engage with their body of work in a way much deeper than a single citation metric.