Games : How to know when a one-on-one is in your advantage in Heroes of the Storm?

Sometimes I end up solo in a lane with some character, and there is another one facing me from the other team... Sometimes, this situation may come in any point on the map.

However, I don't have the experience to know in advance if the duel will be in my advantage or not. Let's say I play Diablo, and I face Valla, and we're both LVL1. Do I have to back ? Do I have a chance ? Is it a tie (in which case any additional friend coming in either side will make the battle balance on his side) ?

I know there are many, many possible situations, depending on the levels, maybe the map... But is there some rule of the thumb (maybe based on roles : DPS beats Warriors, and so on...)