Deadlock

None of these games had as many shooter elements as Deadlock. Like the maps were all just generic wide open MOBA lanes seen from a third person angle, whereas Deadlock's map has tons of cover so the positioning skills you learn as an FPS player can actually translate, particularly in the laning phase. Movement is also way more shooter-reminiscent, in that every character has stamina and universal movement mechanics with a high skill ceiling. A lot of these other third person MOBAs only had movement mechanics built into the hero, at all other times it was fairly basic. The reason why FPS players like myself ignored all those other games is because they were just MOBAs with a different camera angle. Mechanically they were still boring as fuck to play, whereas Deadlock actually has very fun shooter mechanics that are the hook that can get players like myself in and learning all the "boring" but very important MOBA parts.

EDIT: Not arguing with you by the way, just piggybacking off your comment to further explain why this game is different to everything else that came before it.

Monday night combat and it's sequel were around as well, but it's been dead for years as well