Hi Max, welcome to the forum and the Kemper family.
Despite the fact that the KPA sounds incredibly well out of the box and with many of the stock profiles as well as with one which are freely available there is not really a way around digging through a bunch of profiles which suit your needs. Either on RigExchange or from the free/paid ones around in the market. As Jeff rightly said: There is no one size fits all
And be prepared to find rigs which suit your needs quite well but are not from the amplifiers you mentioned above. That's the beauty of the KPA.... you can learn so much about amps you never had (and in my case: I would have never had on my list to try).
Anyway: Bogner Ecstasy.... there is a good one in the KPA already (Guido Bungenstock is really a go to person for that kind of sound). You'll find more in the free pack of the SinMix guys from Poland. They have lots of good metal amps profiled. Extremely good pack to find out a bit more about some amps.
The Roland JC rarely came to my attention. What I like for a wide clean sound with a good portion of effects is Connie Andreszka's ENGL INVADER CH1 HG profile from the RigExchange. That's a great one for pickings with huge sound.
Plexi: I like the ToneJunkie SL Plexi stuff, I found a few free ones of those and RickyStorti's Marshall Plexi 1959 from the RigExchange goes well for me too.
Hope that helps.
Greetings from Germany as well.