I think Arsenal is the favorite of the upcoming match, despite the fact that the team can not win in recent games. Yes, the Gunners are on a losing streak. But the game with Crystal Palace is a good opportunity for the club to break the losing streak. Crystal Palace will not be able to do anything against their opponent, despite the fact that Sallah is absent from the Arsenal squad.
Arsenal is at home and that alone is enough advantage for them regardless of their form especially when playing against weak team such as crystal palace, Arsenal is expected to have nothing but victory by the end of this game, but then a loss is possible but it's one thing arsenal is definitely not expecting or seeing coming not from crystal palace visiting them.
It's still very possible they end the game in a draw as football is a game of surprise and anything can happen at anytime. Brentford have a five unbeaten record against Nottingham forest but then Brentford recently experienced a loss against wolves which got them crashing out of the FA cup over the week, I see that as enough to be affecting their psychology which may inturn extended to their performance but then both teams are just average team and I'm not in much anticipation as to what the outcome will be but then it's important neither of both teams underestimate each other.