Just my personal preference
1.Plain Archive
2.Nova
3.Kimchi
4.Blufans
5.HD Zeta
That's exactly my order too.
Plain Archive
are extraordinary, disciplined, most consistent in artwork, overall quality and most thought through design when it comes to the whole package. Above that they are groundbreaking and paramount. Some titles I even collect purely because they put so much effort into it. Even though I don't really dig the movie, as a fellow graphic designer/enthousiast, you just gotta have their products of beauty.
NovaMedia
releases are always beautiful, they have made a name for releasing beautiful slips and lenti's with awesome depth. With my all time favorite, Captain America 2. By far one of my favorite releases of all time.
Kimchi
is an old king, yet still strong, I feel it's power slowing flowing away. That doesn't mean their releases aren't killer. But the last few releases I couldn't care less, but that's personal ofcourse.
Blufans
Their Steels are simply awesome, but I don't like their overall design when it comes to slips, plus the fact that their slips have the artwork on the other side bothers me. ;-) and for someone who keeps their releases sealed, I can't see the steel when it's sealed.
Hdzeta
I simply cannot get over their hideous stickers. I simply cannot. ;-)
Special note:
Let's not all forget The BluCollection. Not every release is a steel, but they are in their own way very unique and mysterious. I'm beginning to appreciate their art of work a lot and find them a truly groundbreaking outsider. One to watch for sure!