Ana
Ana is one of the better Echo counters, if not the best, due to how she can easily shut down Echo's flight ability and focusing beam. When I have used Ana's sleep dart, she has easily kept Echo out of the match. However, I have found playing Ana can be quite a challenge, so this may take some practice!
Echo is frustrating to attack if the player knows how to use her correctly. The sleep dart, though, is one of your most effective abilities against Echo to ensure bringing her down quickly. Typically, Ana is a hero out of range from Echo's sticky bombs as well, which gives her more advantage to taking her out from far distance. This makes Ana not only a great counter to Echo, but also hard to counter for her abilities!
D. VA
D. Va is the second best counter for Echo in Overwatch 2, and one of the best tank heroes to counter Echo effectively. Her defense matrix does everything to bullet-sponge her way to bringing Echo to her defeat.
Besides the focusing beam, As I have played D. Va Ive learned she can deflect almost every close range and mid-range offensive attack from Echo. This puts this tank hero as one of the best options for me when I am running a tank hero.
Sombra
Sombra is an easy counter for Echo. As her ultimate completely puts down Echo's charge gimmick, which will put her as completely useless during Sombra's Ult. With first-hand experience... I can tell you that Echo really doesn't have a chance against Sombra 1v1.
There is not really anything Echo can do to counter Sombra, as she is always shutting down Echo every time she uses her hacking ability and ultimate. Sombra is a beast of a DPS hero against Echo, and if you are a damage hero main, she should be your first pick!
WidowMaker
Widowmaker is a great counter, even though she is overall a huge counter against many heroes. Her sniper damage output can immediately shut Echo down, as she is extremely weak against high-powered weapons and firepower.
Not only does Widowmaker provide effective damage against Echo, but she also is hard to reach for any Echo player. Due to her long range, it makes it impossible for any of Echo's abilities to reach her and make effective progress.
Pharah
Pharah offers a pretty aggressive defense against Echo, including her combative flight ability that I have had a blast using, shutting down Echo immediately with her rockets.
As a support hero, Pharah makes a large impression against Echo with not only her rockets but also her flight ability which greatly combats Echo as she has major explosives to counter Echo's tri-shot and sticky bombs.
Cassidy
Cassidy has an eagle eye for Echo, specifically to bring her to a full stop. With his ultimate, I can easily use Cassidy to bring Echo down immediately, with nowhere for her to run. He is by far not only one of the best DPS counters, but overall one of my favorite heroes to defeat Echo.
Echo counters are rather simple to determine, and Cassidy is a clear choice with his dodge that can counter Echo with her stick bomb ability and secondary fire. Along with his grenades that gives Echo nowhere to run, Cassidy will set you up for a hardcore victory against Echo.
Bastion
Bastion is a perfect counter against Echo for not only his minigun but also his primary fire. Bastion does not need to make much effort to counter Echo, as he offers major fire support for his entire team creating major damage output.
Bastion is really hard to counter for Echo, although not impossible if she can dodge his ultimate. Echo will need to have a lot of strategy and help from her team to have any chance against Bastion. Out of all the heroes in the damage rotation, Bastion is for sure a huge headache for Echo players.
Roadhog
There's no match against Roadhog's hook once he claims Echo and attacks her with his primary fire. No matter what Echo swings at him, he will barely take any damage from this hero. Even with the sticky bombs, Roadhog has the ability to immediately re-heal without the help of his nearby support hero.
As a tank player, I have a hard time playing as D. VA compared to Roadhog, as he is a great alternative to get me at a great close range without needing too much assistance. However keep in mind that if Echo is with any support, you can struggle to keep up.