Who do you think are the best dps to copy? Doom is pretty good because you can land like one punch and get his ult already. Tracer is ok too because you can reliably get a couple pulse bombs. Who else do you think is worth copying?
I know it’s better to copy tanks 99% of the time. Just asking for fun which dps are best in those niche 1% of cases.
It’s easily echo
If only I could . 
Probably Bap. Jokes aside Ashe because of BOB.
How could I forget Ashe? Only thing is I don’t see that much Ashe in my games lately 
it’s very situational, sometimes I go for Cassidy just for the flashbang scenario, sometimes reaper for blossom, I even at times would argue a quick bastion duplicate can help lmao.
It depends of so many things.
I really enjoy echo as a character and I know that im in the minority when I say she is healthy for the game. Also Ashe has less utility than McOverpowered and tracer.
Bastion since you can do an airdrop Bastion and get instant ult which is one of the better DPS ults. If Echo had his ult just instead of copying, that would break her
EDIT: Downside is obviously that you won’t be seeing them in your games probably
doom or ashe
Hanzo.
Pop storm arrows, get a few hits in and next thing you know you’ve got a dragonstrike barreling down and your enemies panicing. Get a few more headshots in and you can fire two, three, four etc. Between Hanzo and Tracer the ult spam you throw out with her is hilarious.
However Echo is more dependent on the enemy comp because of how duplicate works. So of the two dps the enemy has (or 1 cause echo can’t copy echo) I tend to go for either better abilities/ultimate or burst.
I find that it depends on the situation, however here are my standouts:
Ashe: You are able to gain BOB very quickly. Which can send enemies into disorganization. Her and BOB together is also very strong.
Doomfist: I am not gonna lie and say zipping around the map is not fun. Plus you are free to go all in with Doom.
Tracer: I am not the best Tracer, but spawning Pulse Bombs is nutty and Echo as Tracer can get them very fast. However her health pool is very low so you do got to be more careful with her.
That said there are some targets I would personal avoid, but again its situational.
Sombra: Echo as Sombra is not bad, but the issue is her EMP already last 6 seconds which is about half the duration of Echo’s ult. This often means multiple EMPs are not very beneficial. Unless you can get EMPs very fast, you often only have time to use it once.
Pharah: Sadly the same problem as Pharah herself, you make yourself a still target.
Widow: Echo herself is already very good at scouting and gathering intel. Thus there is often no need for Infra-Sight. Infra-Sight also has the same duration as Echo’s ult witch means you will never get the full duration of Infra-Sight.
Symmetra: Same reason as Widow and Sombra, you will often not be able to cast a second Photon Barrier. In most cases the Photon Barrier’s duration is cut short within the 15 seconds. Making it a downgrade compared to it just being used by Sym.
Again this is just my opinion. I actually still dupe heroes like Sym at times for their ult, even if I cannot get their full potential.
I’m not much of an Echo player at all, but when I do play Echo I always feel copying Doom or Genji is pretty darn good.
Reaper, Sombra, Ashe (as long as you can farm BOB) and probably Cassidy IMO.
Reaper, 2 or even 3 death blossom are nice 
Generally close ranged DPS are really good. So mei, reaper, doom, sym, torb.
Ashe and cassidy are also pretty decent. Cassidys pretty much guaranteed to get a free pick with flashbang and ashe can farm BOB pretty quickly.
Do not dup widow. Unless you are really really good at her.
The correct use of the word is “McCheese”
I feel like Mei ult charges too slow. Maybe I’m just bad with her but when I copy her most times the other team won’t even freeze in her ult before my timer runs out. Reaper is good too if I do it on a flank but if anyone sees me I get focused so hard and can barely get blossom out before I die.
Honestly, I think it depends on the composition and positioning of the enemies. I could copy a character but if they’re positioned in such a way where I can’t hit them fast enough, like through shields or something, then I can’t really get much out of it. I often avoid DPS unless I’m using it as a way to survive from near death, otherwise I would stick to tanks if I can. So, usually it’s a 1v1 situation, or my only option to target, or something that can get me through shields and build ultimate quickly.
Don’t copy DPS. Copy tanks.
Best DPS to copy is Roadhog