I don't think the english top 6 is the strongest in europe.
However I don't think la liga or serie a's top 6 are that strong either.
However the Bundesliga does intrigue me a lot. The top 11 is only separated by 9 points and their top 6 atm looks very strong. Bayern, Schalke, Dortmund, Bremen and Stuttgart are among those spots. Hell atm Hamburg are in the relegation spot! So it intrigues me a lot that league.
I look forward for the next couple of years when the German league will have 4 of its clubs in the CL so aside from Bayern who are a european powerhouse, it will be interesting how the other clubs grow and develop.