This advice is true for many different class-based games, be they massively multiplayer online RPGs like Final Fantasy XIV or competitive games like Dota 2 or, indeed, Overwatch. (Yes, it’s another Overwatch post, for which I make no apologies.)
Overwatch is an interesting case study, though, in that unlike the other examples I gave above, you can change your character and indeed your complete role in the team at any time — either immediately after dying or if you’re back in your base. This leads to a whole new interesting metagame where your team isn’t bound by the principles of the “holy trinity” of tank, healer and damage-dealer (or, in Overwatch’s case, the holy quartet of tank, support, offense and defense) and can instead evolve and change as a match progresses according to the team’s needs.
Because this is such A Thing in Overwatch, you absolutely shouldn’t pick a single character and “main” them like in other character-based games like competitive one-on-one fighters. At the bare minimum, you should be familiar with a hero in each of the four roles, and ideally you should at least know what every hero is capable of, even if you’re not particularly skilled in playing as them.
You can read guides about this, but the best way I’ve found to learn which hero is good against which opponent is simply to experiment and see what happens. That way, you’ll naturally figure out which heroes you enjoy playing and who they’re effective against.
I have a number of heroes that I’ve started gravitating naturally towards so far. I intend to expand my repertoire over time, but for the moment here are my favourites.
In the offense role, I’m a fan of Tracer. Her rapid fire guns immediately hit their target when you fire them, so there’s no need to lead targets in the same way as you need to with those who shoot more obvious projectiles — you still need at least a reasonable degree of precision, though. Her absolute best features are her special abilities, though. Her Blink ability lets her teleport a short distance up to three times in succession, letting her quickly dart across doorways and passages that are covered by dangerous sentry types such as Bastion or Widowmaker. And her Recall ability is great for confusing an enemy, as well as providing a means of self-healing by not only rewinding her location, but also the value her health was at a few seconds ago.
For defense, I like Mei. Her Ice Wall ability is great for blocking off specific routes and funneling the opposing team down a route you can cover more easily. Her weapon also has a great deal of flexibility; the short-range “ice thrower” acts a bit like a flamethrower only, you know, colder, and also has the added benefit of freezing enemies, initially slowing them and eventually freezing them completely for a brief moment. Her alt-fire, meanwhile, fires an immensely accurate icicle bolt that proves devastating to snipers such as Widowmaker, dealing a huge chunk of damage in a single hit at medium to long range. Combine this with her ability to freeze herself, making her temporary invulnerable while self-healing, and her Ultimate, which causes a freeze and damage effect over a decent-sized area, and you have a great defensive hero who is more than capable of going toe-to-toe with dangerous, occasionally insurmountable-seeming threats like Reinhardt.
In the tank role, I enjoy D.Va. D.Va is interesting to me in that she’s not necessarily designed to soak up a huge amount of damage in the same way as some of the other tank characters, but is instead a rather mobile unit that can put out a good amount of close-range damage while having much better survivability behind enemy lines than the Offense heroes. Her absolute best thing, though, is her Ultimate, which self-destructs her mech suit, taking anyone in a significant radius with it, including herself if she doesn’t get out of the way. What’s fun about this ability is that you can combine it with her mech suit’s jump jets ability, effectively “throwing” the self-destructing mech at the enemy team from a distance while she skips off happily into the distance. Also she’s adorable.
Finally, in the support role, I’ve had most success with Lucio. A speedy character with a passive “aura” effect rather than a more active healer like Mercy, Lucio is an excellent support character who is very capable of putting out a decent amount of damage in his own right. His decent mobility thanks to his high speed and Wallride ability allows him to move unpredictably and avoid damage, while the relatively short cooldowns on his abilities let him provide either speed boosts or decent healing to nearby companions on a pretty consistent basis. Not only that, but the fact his buffs and healing work as an aura mean that he can concentrate on wrecking some fools while he’s benefiting the team, meaning he can help out in several ways at once.
I’m sure I’ll discover new favourites in the near future, but for now these are the ones I’ve had the most success — and fun — with.