Cortez, Erin, and OPhelia are all good in PvE.
Cortez is just flat-out 15% better average damage (for HEAT... 10% for AP), and as a side effect grants you the ability to know exactly how much damage each of your shots is going to do. That can be useful at times if you need kills for a mission or something. He's one of the best PvE commanders, especially for pure damage dealing vehicles.
Erin is the best commander for stealth, not vision control. If you need to be stealthy, Erin is your commander. But she isn't good for vision, so for vehicles that already have reasonably decent camo, Juan Carlos is better for overall vision control. (He grants a small amount of camo, but a very large VR bonus.)
OPhelia has good ROF boost that come with negatives, but is primarily useful for her shield. That's super useful for crunchy vehicles that have a tendency to get spotted and instantly evaporate in PvE. I've migrated away from her mostly, though, because with most vehicles I can avoid being spotted consistently enough that I don't need OPhelia's shield. There are a few where it's still useful so that I can play aggressively, though, such as Terminators.
Austin is just bad. Avoid.
Alisa has a couple of quirky uses - extra ammo and ramming damage builds - but is otherwise uninteresting. Time-to-kill is so low in PvE these days that her main ability - the off-map ally that randomly shoots missiles at her targets - is too slow to be useful. She might suit your playstyle on a handful of vehicles, but what's more likely is that you'll experiment with her a few times and then never use her again. So probably not worth paying for.