I hate Epica.
I hate every Nightwish ripoff there is out there. And it's not because I'm pro-Nightwish but I hate fucking copycats.
And I absolutely vomit on this:
http://www.youtube.com/watch?v=sGgY8nm22UE
The bolded part sort of assumes Nightwish created the style. While I'll say that Nightwish were an early innovator in the female fronted symphonic metal world, Within Temptation also started in 1996 and technically released their first album
Enter prior to
Angels Fall First and one could also argue that bands like Theater of Tragedy did the quasi-operatic vocals years before Nightwish with Liv Kristine. I'd probably also put Epica and it's consistent use of beauty and the beast vocalizations more in the ToT camp than Nightwish. Modern Epica is much more progressive oriented than Nightwish would ever dream of being so once again they are far from a Nightwish "copycat" as you call them.
As for Floor Jansen, while once again they have the similarity of being a female fronted symphonic metal band, they were always more in the gothic camp and but also wrote about completely different topical matter then faeries, elves, and Broadway musical subjects common in Nightwish's catalog. I'll give you a certain commonality between Epica and After Forever since Mark Jansen has been the primary songwriter for both, he has always mixed in a variety of stylings to the music he writes - using a much greater variety of metal sub-genres than Tuomas Holopainen ever has in Nightwish.
With the whole "copycat" theme you seem to despise so much I'd imagine you have a pretty hard time with almost every record released in the last 10 years since the majority of modern metal is from a pretty simple cut, copy, paste methodology with limited true originality existing in very few bands these days. Personally I've always been a believer in the fact that almost every great riff has already been written - were all just slowing them down, speeding them up, or simply joining them together in differing ways. What really counts as originality these days? Me, I just appreciate when a band does what they do well regardless whether they are the innovators or simply doing something that already existed in an enjoyable fashion.
As always, individual mileage may vary.