Compared to Erik Ten Hag, I think for some reason I prefer Niko Kovac because I think he has quite good experience in the Bundesliga and maybe he is suitable to coach a big club like Dortmund, previously he was the coach of Bayern Munich and won the Bundesliga title and the DFB Cup in the 2018-19 season and also became the coach of Eintracht Frankfurt winning the DFB Cup title and the Runner-up position in the Bundesliga so if he coaches Dortmund, it is possible that he can improve the performance of this club which is currently slumping.
Borrusia Dortmund case is complicated due to the unstable poor performing stats of the club. They're elite team and should sits in position to win titles and not be contended with the current situations. The Bundesliga title is pointed between Bayern Munich and Bayer Leverkusen. The board sacking their manager becomes some sort of mediocre because they're ranked 10th position on Bundesliga table. The management making decisive options to either settle for Niko Kovac or Erik Ten Hag. Perhaps the odds of appointing Niko Kovac is higher based on his past records in Germany. They're looking for a manager that suits into the system and will deliver a perfect managerial role. Kovac gained enough experience to lead Borrusia Dortmund but this solely doesn't applied to the current form, he will restructure the team.