I find Regenerative shields best with x3 regen mod on the shield for Cruiser or Sci ships. On Escort I just go highest cap. Even a Macro tends to underperform against a decent regen setup. With a decent regen setup you are not going to die to anything 1v1 or even often 2 or 3 v 1.
EDIT: I should have said the above assume 125 shield power. Without 100 to 125 power regen shields are not worth it. A regen setup is like having EptS every 6 seconds from a healing hitpoint prospective.
Covariant shields to me, are good for escorts beacouse you have a big "buffer" and with a limited Boff skills you can raise them.
Covariant for escorts are the way to go, IMO. Escorts can't take the time to heal with shield regen. Escorts are glass cannons, but a Fleet Escort w/an Engineering main can tank with a Covariant, since it allows you to run in on a full-on attack, then turn around for another run while using your aft. That's how I run it and I rarely blow up. I don't do Elite STFs, though, and that should be noted to the reader.
I use Resilient shields on my luna class RSV. I have quote a few abilites to bloster them back up, and I run with two EPtS anyways. If I hit all of my "oh ****" buttons at once, I can survive pretty much anything. Itks the bleed through I have to worry about because if anthing touches my hull, I am limping.
Haven't played other classes, but I would think regeneration on an escort, because you tend to got on bombing runns anyways, you zoom in, blast away, the pass them and swing around for another pass. That time it takes you to swing around is the only time you have to recharge your foree shield. And you can wipe around fast enough to move a naked hull out or firing range.
But then again, I have never tried this first hand. So feel free to prove me wrong.