Titans season 2 introduced Slade Wilson (aka Deathstroke) - and it's a vastly superior iteration to the one from the Arrowverse. Created by Marv Wolfman and George Perez, the assassin is relatively new compared to many characters, yet after debuting in the comics in The New Teen Titans #2, he has gone on to achieve immense popularity with fans and is widely considered to be one of the greatest villains of all time. In the years since, Deathstroke has branched out to battle such A-List heroes as Batman and even the X-Men in one particular crossover. Living up to his name, Slade has come out victorious on numerous occasions.
Played by Manu Bennett, a live-action version of the character debuted on Arrow season one. Starting off as a mentor to Oliver Queen, Slade took a villainous term in season 2 as a result of the Mirakuru drug and the death of Shado. Though believed to have died on Lian Yu, he proved very much alive and reemerged in then Starling City to enact his revenge. Titans' version, meanwhile, is played by Esai Morales. Revealed in the season 2 premiere to be in retirement, he resumed active duty upon learning from a news report that Dick Grayson's titular group had reformed. Ever since, he has tormented the fledging heroes on multiple fronts as it slowly emerged that he holds them responsible for the death of his son, Jericho.
While Bennett's turn is not without a certain charisma and a whole host of merits, the reasons for Titans' version being superior are myriad. Whether in and out of the mask, this Deathstroke is as much a force of nature as in the comics. There, Slade Wilson is nicknamed The Terminator for a reason. And, on Titans, that reason has been demonstrated repeatedly, whether against random targets or the Titans themselves. Where most villains tend to degrade as a season progresses - with their plots increasingly undone and their strength progressively depowered after an explosive start - Morales' Slade has shown no such signs. In fact, nine episodes in, he has consistently proven himself steps ahead. As well as single-handedly provoking the Titans to disband once more with his mind-games, he is also undefeated against them in combat - both in flashbacks and the present day.
In an earlier episode, Donna Troy stated that Titans 1.0 were lucky to crawl away during their first run-in with Slade Wilson. The most recent flashback revealed that statement to be all-too literal. Revealed to have wiped out San Francisco's chapter of Amazons, Deathstroke handily defeated Wonder Girl in combat - leaving her broken and bloodied while he walked away with nary a scratch. Deathstroke would go on to easily defeat Dick Grayson later in the episode. The only reason Donna lived to tell the tale was because Slade himself willed it so. And Dick only survived by the intervention of Jericho - an act which presumably prompted Deathstroke's aforementioned retirement. Equally, in the present, had it not been for the well-timed arrival of Superboy, Deathstroke would've succeeded in adding Jason Todd to a list of dead Titans that already included Aqualad.
As such, Morale's Deathstroke was accurate when he told Jason that he should be terrified - because he is terrifying. With only a few episodes remaining, it looks increasingly likely that the only thing that will be able to prompt his defeat is the theorized possession of his body by Jericho. Conversely, it always felt inevitable that Team Arrow would emerge victorious against Bennett's Deathstroke. After all, despite Slade having newly emerging superpowers, decades more experience, and even having trained him personally, Oliver was still able to take his eye and leave him for dead. Though he inflicted some serious psychological damage later on, especially in killing Oliver's mother, he entered at a disadvantage and his defeat always remained a foregone conclusion. Morales' version, however, holds on the cards. As such, though many will have their own preference between Titans' version and that of the Arrowverse, only one Terminator has truly lived up to that title.