Regen sequence. Can outtank 6 beam lasers while you only need one. Totally broken and unbalanced but can heal while your target is under fire.
Are you sure that's still the case? A while back, it was changed to not ignore resistances, iirc. I think it now does as much healing as an equivalent enemy beam does damage.
On topic:
I prefer concodant sequence, as the DPS of the beam doesn't matter, and the effect lasts for a few seconds. Note that it only multiplies the natural regen of the target; if they're constantly getting hit, it won't have any effect.