Simple. Which team comp do you think is the best? It can be more than one combination. You don't necessarily have to own it. Do you think all comps need a tank? Does positioning really matter? Why build a team comp out of 3 different characters when you can build a comp with 3 of the same overpowered one? Is element variety important? Do you adjust your team's elements to counter the meta? Wouldn't it be cool for each team to get some kind of bonus during fights depending on your comp? Does any of this makes sense?