It's better for Watkins to join Arsenal than Manchester United, Manchester United still have many problem in every positions, so this will be hard for new player need to adapt. While Arsenal is already a complete team, they only lack of striker, Watkins also always become top scorer in Aston Villa for four season in a row. Even though Havertz recently played quite well, but he's not a pure striker.
So far, Ollie Watkins has often become a real threat and also often continues to destroy their opponent's goal so far, so he should be the target of many teams to be able to sign him next season, Manchester United are of course targeting Ollie Watkins because they need a striker who is sharp enough to undergo next season, currently Manchester United have Anthony and Hojlund in their front line but so far Anthony has not been able to show performance Which is quite good after being recruited from Ajax last season, but fortunately now Manchester United has Hojlund Although unable to lift Manchester United performance to the maximum, but Hojlund still has a big role in the Manchester United squad this season.
Manchester United are likely to try to sign a lot of players next season to improve their form and Watkins will be the main target of Manchester United, but for now the question is, will Watkins want to waste his chance to play in the Champions League next season just to play in the Europa League with Manchester United?
I think of course not, but it could happen if Aston Villa sell him for a high price to Manchester United later, if there is an option of course Arsenal could be a more appropriate choice for Watkins and I think Arteta will make him the main attacker if he joins Arsenal, because indeed he looks more dangerous in front of goal than Jesus and also Kai Harvest.