I've been wondering the exact same thing. I'm typing this on my Epomaker EP84, and may still order the K2 Hotswap. It's been a month since you posted. I'm surprised this hasn't been discussed more. Please let me know what you've learned or decided. I've been all over the Google/Youtube-verse trying to understand which is better. After a week of owning the KC/EP84, there's a lot to love, but some letdowns and support questions.
I'm going to make a video of my adventures, but in short:
EP/KC84 is a nice, simple, solid, Leopold-style build with bad backlighting and nice feeling, decent looking backlit keycaps. It's capable of limited reprogramming, but the software kinda sucks and won't ever be supported by Epomaker. The keyboard has been around in some form for over five years, and judging by my emails with Epomaker, is likely getting phased out. Still, it really hits the 'budget Leopold' mark it aims for. The biggest deal-breaker I can find is that the dim lighting prevents legibility in a daylit room, at least on the lighter alphas. It's pleasant on the black keys, almost as if you can change the dyed color. Aside from that, hard to complain. Once I swapped on non-backlit caps, it's pretty great. There are nice 'custom' touches, like sound deadening foam in the case and decently lubed stabilizers. I still don't know whether or not to return it, due to such limited software support and the need for replacement caps to read them. Perhaps just find one without backlit keycaps.
K2 Hotswap is a brand-new, slightly more complete package (in theory, I haven't yet recieved it). Impressions of Keychron's rgb are mixed, but most people agree that the white backlight version is bright and functional. The Keychron's legends are legible even without a backlight, and reviews have said the abs on the new K2 is pretty good; similar thickness (~1.2mm) and texture to the KC84's pbt, with much nicer legends. A Keychron rep emailed me that Keychron will release software to reprogram the K2 in mid-2021, so the KC84 will soon loose that (weak) advantage. They'll also sell the K2 Hotswap on Amazon within 2-3 months, if you want to wait and take advantage of their shipping and returns. If you get a KC84 without backlit caps, the price advantage is kinda there, but the K2 will offer more universal use and extended support. Keychron no longer make a version without a nice bluetooth module and battery. Even if you get the wireless KC84, the older bluetooth tech is not as good.
Despite the warts, I'm growing pretty attached to the EP84. If I were to return it, I might miss the chunky, simple case and simple-done-right feel....but then there's my ipad and this nest of wires I'm always dragging around, and the fact I had to cannibalize another board for legible caps....
I hope this helps anyone comparing the two. Please let me know what you think.