With a busy schedule and each team requiring player rotation, it means the competition is even more interesting to watch. Manchester City has a tier 2 squad that is equal in terms of play so Pep Guardiola can still overcome the busy schedule by adjusting the level of competition between the UCL and the Premier League. the reason is that these 2 competitions are the most prioritized targets for Manchester City while Liverpool because this season is not in the UCL, might be able to take advantage of the situation a little besides having to continue hunting in the Europa League where their opponents are not comparable to Manchester City's opponents in the UCL. For Arsenal itself, in my opinion they won't have much hope in the UCL, so Arteta wants to conquer the Premier League first at least to improve last season slipping performance.
Comparing all the teams that are competing for the English Premier League I think Manchester City stands a better chance of winning the competition. They have one of the best and most experienced coaches who have enough players to select from. I recalled last season when Arsenal began to lose momentum due to injuries and other challenges, while City who was even competing for the UCL kept pushing until they overtook the Gunners. Liverpool is another team that will win the EPL if City fails to win it.
I don't think the Europa League is less tough than the Champions League. Don't forget that some clubs that were knocked out of the UCL will be moving to the Europa League which might make the competition tougher. I also think that the Europa Cup is very important to Liverpool, so they will do their best to win the competition. Arsenal has all it takes to compete favourably in the UCL and I predict that they will overcome Porto in the round of sixteen. There is no need to underrate Arsenal in the UCL because they could just be lucky this season.