What should I look for in ceramics that I am missing?
It seems to me that the only thing that distinguishes one ceramic chip from another is the art work. The designers are able to do very attractive things with a lot more real estate to work with, at the cost of forsaking other interesting design features. DDLM comes to mind.
I am finding that clays and china slays grab my imagination better. Inlays, labels, molds, spots all seem more interesting to me.
The one exception seems to be Cards Molds. They actually have a mold feature to add interest.
BG did a good job outlining the different
physical characteristics of different ceramics, which mostly play into how they feel and how they handle.
A lot of what you've asked about above is about different
visual characteristics, i.e. the designs. Ceramics have a different design idiom than clays which is entirely due to the very different ways in which the two are manufactured. Clays naturally have debossed molds and edge spots and inlays (or hotstamps) and good clay designs make the best of those three features while respecting their limitations. Ceramics on the other hand have freedom to print anything across the entire face and along the rolling edge; they don't have edge spots or molds and don't have an unprintable rim around a central inlay.
That's why you get clays that look like this:
And ceramics that look like this:
Then there's plastics, which have
yet another entirely different design idiom. Like clays, they have a central full-color printed design (on an adhesive decal rather than on an inlaid inlay), but rather than having crude edge spots ("inserts", made by cutting out chunks of clay and placing different-colored chunks of clay back in) they can have a wide variety of patterns in the ring outside the central area, made using whatever shapes are built into the injection molds.
Most of the cheaper plastic chips have "edge spot" designs which are simpler and uglier than typical clay chips. But some have designs that are intricate and interesting. For example:
Two somewhat recent developments are
molded ceramics and
hybrid ceramics. Molded ceramics have debossed impressions in the rim, similar to the sorts of edge molds that clay chips have. Accordingly, PCF designers have been making various clones and tributes to casino clays and replicating those designs on the Tina cards mold chips. They don't actually resemble the original clay chips, because the clay edge spots ("inserts") can't be faithfully replicated just by using printed ink, but a lot of folks think they look pretty nice anyway:
Whereas hybrid ceramics have a central recess which takes an adhesive decal, similar to the way plastics do, and so a lot of designers have been using hybrids to replicate the sorts of designs you see on plastics:
... while others use hybrids to replicate clays:
This is just a crude overview of the common design idioms found on some of the commonly-produced chips. This by no means exhausts the design space; in fact, I'm sure designers will continue to come up with new ideas that expand the range of possibilities. Part of the chipping hobby is getting exposed to the wide range of possible designs that exist - each one relying on different physical characteristics and manufacturing processes involved in creating the underlying chip - and deciding for yourself what types of chips and designs appeal to you.
Good luck and have fun!