Guild Wars 2

There should be a map where you have an option to play 1 vs 1 against a class of your choice or a random class.
For instance you are an engineer and want to fight 1vs 1 against a warrior, than you select warrior from the list and get paired with a warrior who is interested to test himself against an engineer.
Or you want to do 1vs 1 pvp but don’t care about the other class, than you choose class: random.

Never take 1v1 seriously…..

The game is focused around 5v5 so it’s very unlikely to happen.You can ask for a duel on map and create a private server tough.

Plenty of custom arenas are entirely dedicated towards this