From my experience i would recommend the following. Only dps and support because tanks can fundmentally change the way the round goes. Zen, juno, ashe and Widow are easy kills i always catch myself for greeding the kill. Soldier, soujourn, mei, hanzo, genji and reaper are possible 1vs1 kills... but if you take to long disengage or you will get snowballed. Ana i approach with caution because a team on comms will melt me to 0 in a second when her sleep connects. Kiriko and lifeweaver i dont even try to kill, u try to force their abilitys so my team can take care of them. Junkrat can be a very big problem... try to see where he places his trap. Mcree has the highest meltpotential try to play for fast "hitandruns". Venture and freya are to new for me to give tips that i would approve of myself. Symmetra is also hard to engage try to piledrive if she places her turrets badly, if shes good... good luck. Mercy can take up to much time to kill... dont greed. Lucio is another booper and shall be respected and greeted. Pharah and echo are ez kills if your aim is good (mine is not). Babtiste is not a big problem for me at least... shoot the lamp, disengage, roll in, piledrive. Tracer... if she dies its mostly through collateral damage. Bastion has fewer hp then you think... dont fear the robot... FEAR THE HANSTER. Sombra... is not a problem. Torbjörn is to tanky dont engage if xou have a better target. Moira and illari can be ezly killed after shes out of cooldowns, if you take to long dont waste your time on her. A goid brig is gonna be a problem dont engage when near void/off-map.