So far, I can say I've really gotten to love playing Lucio. Of course, with my shitty laptop framerate, he's about the only hero I can play effectively, but I was planning on maining support anyway, so it's not so bad.
As for dealing with Bastion, you have the obvious Genji and Roadhog answers, but if you can get on the same level as him, Reinhardt's charge can get him out of sentry mode and even kill him if you angle it right. I would suggest scouting with the shield first (of course, any Reinhardt with half a brain will be doing that anyway). If you can aim with someone who can do burst damage from distance without an ult (namely, Junkrat or Pharah), that also works. Pretty sure you can kill him faster than he can repair.
As for dealing with Bastion, you have the obvious Genji and Roadhog answers, but if you can get on the same level as him, Reinhardt's charge can get him out of sentry mode and even kill him if you angle it right. I would suggest scouting with the shield first (of course, any Reinhardt with half a brain will be doing that anyway). If you can aim with someone who can do burst damage from distance without an ult (namely, Junkrat or Pharah), that also works. Pretty sure you can kill him faster than he can repair.