PC or Mac for music production

I am using a PC for music production my whole life but I am also very excited about Apple-hardware and software.
Because my PC needs to be upgraded or replaced I am seriously considering an Apple iMac.

Most of the time I am producing Electronic Dance Music or Pop music recording vocals, guitarplay and lots of VST instruments. Cubase 8 Pro, Nexus 2, East West Symphonic Orchestra, Voices of Pasion, Choirs, Omnisphere, Sylenth 1, FX Pansion Geist are synths I use in my productions. I use a lot of resources for my tracks, like 40 channels is very common.

First of all, how is the performance doing on a Mac. When I look at the Apple Store even the highest iMac doesn’t have a i7 processor.

What Apple-computer would you recommend?

Seen the price differences in Apple or PC, what would you buy?