The current meta is kind of all over the place. It seems as though we have a mix of the traditional 2/2/2 meta (2 DPS, 2 Tanks, 2 Healers) and the "Triple Tank" meta (3 Tanks, 2 Healers, 1 DPS). Dive comps are also starting to make appearances, meaning Winston is seen a lot more in games, and also means that you'll see a lot more flankers (Genji, Tracer) on the opposing team. Pharmercy (Pharah with Mercy) continues to be a force that is incredibly difficult to stop on consoles. With Mercy pocketing a Pharah with heals, it's near impossible for Pharahs direct counters (McCree, S:76) to kill her effectively, especially if the Pharah stays out of their effective range. All of the Offense heroes, barring Reaper and McCree appear to be in the meta in some way. Tracer and Genji are perfect for "dive comps", flanking the opposition, and eliminating healers quickly). S:76 and Pharah are great for raw, upfront damage, and Sombra, despite her incredibly low pick rate, is perfect for shield dependant, or tank heavy teams. McCree is simply a worse Soldier (worse mobility, harder to use, horrific ultimate, can't self-heal, etc), and everything Reaper does, Roadhog can do a lot better, with the added benefit of being able to heal 300 health every 8 seconds or so.
Defence heroes are so-so right about now. Mei is pretty good for stalling a point, but her usability falls off by quite a lot the further you climb up the competitive ladder. Bastion, while being pretty powerful, doesn't see that much usage, which is pretty shocking. He's pretty good for taking Pharahs out, considering his effective range is slightly better than McCrees and Soldiers. I wouldn't bother with anyone else. Torbjorn can be an ok pick for a 2CP map (Volskaya, Anubis, Hanamura), but this is incredibly situational. Other than that...nah. Junkrat does have high usage in Platinum, but he's not a very good pick; despite doing good damage with his grenades, his accuracy with said grenades is bad enough that he might not get a kill with them, which feeds the ults of healers, and if the opposing team has one, Sombra. In addition to this, his grenades are the perfect way for Zarya players to charge up their damage to ridiculous levels, which is again, feeding the enemy team. Couple this with his incredibly mediocre ultimate, and it's not a good combination against a team that might be using a solid composition against you.
Currently, every tank has a place in the meta. Winston, D.Va and Zarya are amazing for dive comps, Rein is the anchor tank, and Roadhog and Orisa have the pure DPS to take on a lot of heroes. All of their ultimates, barring D.Va's, are incredibly powerful, too (D.Va's ult can be powerful, but when you climb up the ladder, needs a lot more coordination and teamwork for it so work; otherwise, it's just a way for the enemy team to run off of the point for a couple seconds. However, looking at the PTR changes, Roadhog is about to be severely nerfed. His damage is being reduced by 33%, meaning that his Hook+Shoot combo isn't a guaranteed pick on the squishier heroes anymore. Couple this with his reduced damage overall, and Roadhog might just be a walking ult battery.
Support heroes are also in a great place. After his somewhat recent buffs, Lucio is even stronger than he was before, allowing him to actual deal good damage to other heroes. His speed boost is also great, and his healing, while not the best, really gets the job done. Sound Barrier is a solid ultimate too, provided a Sombra isn't on the other team to counter it immediately with an EMP. Nothing to say about Ana. She's been in the meta since her release, and shows no signs of dropping out, considering she has an incredible ultimate (provided you don't boost a Lucio or a Mercy) and the best healing in the game. Mercy usage appears to have increased dramatically as the seasons go by, mainly due to the fact that she's incredibly easy to use, and is probably the easiest hero to "one trick" and climb with (I have someone on my friends list who I last played with in Season 3; he made it to high plat/low diamond by the end of the season before becoming a "Mercy one trick". At the end of Season 4, he was at the very bottom of Grandmaster; around 200SR or so from being in the Top 500). Ultimate is still incredibly powerful; even more so now that she's completely invulnerable when casting it. If you kill a Mercy on a point, then kill the rest of her team a short while after, do everything in your power to make sure she does not get back to the point. There has been times where a Zarya has simply burned her ultimate (which takes an incredibly long time to charge) just to stop a Mercy from resurrecting her teammates. Always remember; kill the Mercy first, not 11th. Zenyatta is a great healer for dive comps, and when he wants, can put out a simply ridiculous amount of damage in a short amount of time (this is balanced out by his mediocre healing capabilities). Always be careful when there is an Ana, or a Sombra on the opposing team. If an Ana hits your team with a Biotic Grenade while they are under Transcendance, the ult is made useless, and a Genji could run up and wipe out the team while they are all bunched up. If Sombra hits you with an EMP, you can't heal your teammates, can't increase damage done to enemies, and most importamtly, you're left with 50HP (as Zenyatta has 150HP made up of shields, and these are broken instantly by EMP), meaning that you can be killed very easily. Symettra isn't as 'meta' as the other support heroes as she's pretty situational, but can be pretty strong on the first points of 2CP and Hybrid maps. She's exceptionally strong on Eichenwalde, as she can block off both the main chokepoint, and the side room, leaving just the right flank left; which only Pharah can reach. What's more, her ult charges incredibly quickly; Teleporters are incredibly useful, if they aren't found first.