The #1 feature I miss most from OW1 was “Looking for Group”. I met so many friends through LFG that I would play with regularly, plus playing in a full group with everyone communicating is peak overWatch. 
Meanwhile, solo-queue is a terrible experience, because no one ever communicates (except to be toxic 
) in a game based on teamwork. I like making call-outs when I play, but can’t because most of my teammates don’t even join the voice-channel.
Since OW2 has been slowly bringing back many of the features removed from OW1 (6v6, lootbox, etc.), I hope LFG makes a return too.