JACK is very important, but on Inconceivable and Master difficulty JACK is played more conservatively and is more about being a medic and smelting weapjns at the Forge.
My only little complaint is that JACK is relied upon so much to be the main medic in the team that the Horde meta involves just him and no one else. In an ideal world there would be another viable medic character.
I get that the COG Gear is a possible option, but I just don’t think they’re on the same level by a long shot (as a medic). As the OP says JACK can heal and revive from range, and can cloak.
I had an idea for the COG Gear that they had the ability to revive team mates from a distance away too. Not as big a distance as JACK - maybe the COG Gear can have a revive radius around him of about 3 metres.
Also enable his Team Revive to bring back dead team mates (not just DBNO) and maybe a card which buffs nearby team mates (team mates within 10 metres receive a small health regeneration boost?).
The COG Gear has much better combat ability than JACK, so the healing buffs don’t need to be major. It would give players a real alternative to JACK.
But equally it would be nice if JACK had a little buff in that regard too. Maybe if he had a card which allows his zapper to chain multiple enemies? It’s pretty weak as it is, so would just be for crowd control support.
And on a side note, just to make the Forge more viable for other characters too, maybe add a passive ability to Scout characters giving them an extra boost when they smelt weapons? Again, not JACK levels of power but somewhere in between.
For me personally, it would be nice if each role in Horde teams could be fulfilled by more than one character. I like variety.