Like ive said, i can understand both sides of the question, and of course the fluctuation of the teams quality varies from year to year and it has to be applied to the equation.
Good examples of that atm are Chelsea and Leicester.
But im not sure if my english is incorrect or if its you who´s not reading correctly.
Imo the PL is the most competitive football league, but the CL is more difficult to win, cause its the competition between the best teams.
If you ask me which competition is harder to win, competition between the best PL teams, or the competition between the best PL teams + Barça, Real, Bayern, Juve ... ? My answer is obvious.
Of course, and like youve pointed out, there are allways exceptions to the rules, but you dont see the teams sparing their players for the home competitions, when they have CL matches, do you?