Not Ten Hag and his players, but I think Manchester City is the strongest competitor for Arsenal and in fact, Manchester City has a better chance of winning the Premier League title now that Guardiola has taken over the team and the improvements they have made. In the past few years since Guardiola has joined this team, they have won the premier league on several occasions and they can win it again in the near future.
There's numerous managers that pull a big threat for Mikel Arteta, not only Pep Guardiola. The gunners did an amazing job by portraying a competitive race against the cityzens. Let's say, Gunners ran out of luck towards ending of the league campaign, they started with an impressive start, and not ending lifting the title is something that baffles both the coach, the players and leaving the supporters hope and chant shattered. However they could always returned back to the league with more additional performance, Mikel Arteta is using this time to fixed the weak spots on his squad.
Last season, The Gunner troops ran out of mentality due to the start of the season by maximizing their performance so they forgot that the competition continued long enough. With the lessons that have been experienced for Arteta last season's results are very important to improve the mentality of his players again. At a young age Arsenal players are still a little shaky when faced with experienced opponents. So he will put the pre-season preparations to good use. Arteta continues to believe in himself and with that belief, he can improve good results. However, the biggest challenge lies with Pep Guardiola's club, which has become the number 1 competitor in the Premier League. The rest, like Manchester United, Newcastle, and Liverpool, have a 50:50 probability.