English Teams > Italian Teams
First of b AC Milan and Juventus have always been the major players in the Champions league for Italy. Ac is in a bit of a crisis all their players have aged and they seem to be going through a bit of a transition period.
As for Juventus they are rebuilding its not east loosing all the players they lost and coming back up from the second division so both teams are excused.
Inter where never really big in the Champions league so I don't see why people act surprised same with Roma.
Now if you want to talk about Seria A vs EPL than the whole of the Seria A is much better than the whole of EPL. Besides the big four teams in EPL the Seria A is overall a much better league. Manchester United and Chelsea rarely loose or draw a game with the other teams besides the big four.
Normal mid-table and bottom Seria A teams win games against the big four in Italy. Also look at the Uefa cup English teams never go far. Remember Middlesbrough made the final and got raped by Sevilla. Besides that NOTHING.
Overall La Leiga >> Seria A >> EPL.
Remember Geona, Fieorentina, Lazio, Atlanta, Napoli, Cagliari, Palermo, Udinese, Catania and Sampdoria are better than the other EPL teams besides the big 4.
As for Italys top four I explained above what they are going through.
RealMadrid have been fucked up for some years now, Valencia fell off same with Depor. When all them teams come back you won't be seeing many English teams in the Quarters of the CL.
Don't get too excited Barcelona are still in it same with Bayern, Villareal and Athletico. Watch the English teams get faded.