How do dps rank currently?

Runemage is King for potential, followed by Scoundrel and Ranger, then Shaman.

Current leaderboards can be found here: https://leaderboard-orbus.xyz/

Edit: Warrior/Paladin numbers are not accurate to raid/dungeon damage.

From what I've seen I'll give a rough estimate

I'm going to rank them in terms of potential damage caps, and then a little explanation of where they generally fall in more average settings.

#1: Scoundrel takes the cake for top potential damage simply because of its nearly limitless potential with absurd bleeds, but it does tend to fall in the middle of the pack, and on average, falls behind high end runemages. That being said, the simplicity of the class can sometimes outshine in higher difficulty fights such as Napur hard mode because all other classes tend to suffer immensely due to the high movement that doesn't effect Scoundrels as much.

#2: Runemage comes in #2 at potential damage. Now I suppose ranger with some lucky bleeds can possibly go higher, I have never seen or heard of it so I suppose runemage takes 2nd in potential, and #1 in average.

#3: Ranger comes in third because it's potential damage has some high spikes and I've heard some reliable sources say they can break 100k on a perfect run, which shaman will never do unless the fight is 10 seconds long.

#4: Shaman comes in 4th for potential damage because it does have a very hard ceiling, that being said, shaman can arguably be put in 2nd place for average due to the difficulty of other classes. Not to say the good players would average less than a shaman on most fights, but the average shaman can pull out its highest potential damage with some ease, where the other classes take a bit more time to master and can lower the average across all players. So if you want something consistent and a strong average damage, Shaman is a great choice, but you won't be hitting absurd numbers with the class.

So you have the top potential dps ranks above, if you don't want to read it all for explanations on the averages, I'll say the average ranks here simply:
#1 Runemage
#2 shaman
#3 Scoundrel
#4 Ranger

Let me be clear, skill level will drastically change all averages and potential for each class, a runemage casting 1 per second fireballs likely isn't going to beat out an average shaman. If a ranger is missing half their shots or not maintaining their buff from attacking at range they will fall behind most every class, same with scoundrels failing to get curve shots or proc tiles. There is a lot to consider so I've done my best to generalize here, but your experience may be very different, It's best to play the class you enjoy the most, you can worry about damage potential after because if you master the class you enjoy, you will always have groups happy to bring you along.

These are my opinions, someone else may dispute them but I feel that I've done quite a lot of parsing for every class with arguably some of the best players of each class, and this is the impression I've retained from that experience. I'd be happy to hear if someone has a different opinion.