Zarya is so great, man. I wish people would talk about her playstyle more. Shielding teammates at the perfect time is a wonderful feeling - getting them off on a player right before or after a Roadhog hook, protecting your ulting McCrees and Pharahs, saving someone from a Rein charge, saving both yourself and another from Junkrat's tire, etc - and at max energy she just melts targets.
Speaking of Junkrat's tire, I think some people may not realize that about Zarya's shields - they prevent overkill damage. Anything that would have hit you for automatic lethal damage just won't kill you if you have that shield up. That's why she can protect people from stuff like Junkrat's ult and Reinhardt's charge. Very often if I think my team won't get to the tire in team, I'll just try to intercept and tank it with my self-barrier.
Really good mix of survivability, damage, and strong utility to your team through her barriers and A+ ult. She's just so good.
She's also my both my most-played and highest winrate hero. The natural leadership postion tanks take combined with how great Zarya is at saving both herself and others from lethal damage means she's probably one of the best solo-queue heroes.