So many choices.
I just received pre-production samples came in for my game, The Modern Games Deck. It's been a journey selecting materials and finishes and coordinating with manufacturers. I thought I'd share some interesting things I learned along the way.
Linen vs Plain Finish
I printed samples in both linen and non-linen finishes. You can see the difference below. I and play-testers noticed that the UV-coating-only was a little slick and hard to pick up off the table.
I was warned about issues with image crispness when using linen finish. I didn't see any difference in crispness, but the finish does diffuse light, making the blacks a little less deep. This is definitely a trade off - I prefer the colors on the slick cards, but prefer the feel of the linen finish.
I've also gotten feedback from other game designers that linen finish can make your cards more prone to scratching and wear and tear. For that reason they recommend only going with linen finish for cards that aren't shuffled especially often.
Different manufacturers may have different names for their finishes. If your manufacturer offers both 'varnish' and 'lamination', I believe the lamination is closer to what TheGameCrafter lists as 'UV protective coating'.
Paper Core and Weights
Did you know card printing uses special paper with a thin piece of opaque plastic in the middle? This prevents bleed-through and transparency. You can use black or white core, but black is more opaque and has better guarantees that card front printing won't be visible through the card. (White core is cheaper, though). Personally I don't think there's a good reason to go with white core, unless I guess if the cards will never need their information to be secret and you're very sure your back design is light enough that it won't show through.
Cards also come in different weights, measured in grams per square meter. TheGameCrafter prints 320gsm. Elsewhere I've found 310gsm to be more common and much easier to find. Here is the thickness difference for 10 cards of each paper weight:
The visual difference is minimal. I found the hand feel to be just barely noticeable. A little over half of the playtesters I surveyed said they could feel a difference.
Bridge vs Poker Size
Another thing that is less standard than you might think is card size. Standard poker cards are 2.5"x3.5". Bridge cards (which you usually see in casinos, and may have played with more) are 2"x3.5". You can see the difference below:
I went with poker size because these cards have content that really shouldn't interact or interfere with each other. If you're looking to make card to put across the table poker size is a reasonable bet. If you plan for players to hold large hands of cards, consider bridge size.
Production in China
Remember that import duties, shipping, customization fees, and minimum order quantities exist. Shipping that I was quoted was typically on the order of $500+. As a rule of thumb I'd expect the final cost of an order to double or more above your initially quoted cost. This can still be cost effective, however, especially with larger orders.
I'd recommend for orders smaller than 80 or 100 consider on demand printing from US companies/suppliers. At sizes above that it becomes feasible to consider overseas manufacturers, depending on the specifics of your project.
Game Token Recommendations
I tested out several different kinds of tokens and have opinions. The cheapest you'll find are winks (also called bingo chips), but they are pretty small and pretty slick. Other options include smooth 23mm chips and clay or plastic poker chips.
My favorite are 23mm ones with knurling (grippy ribs on the sides), which is what I've decided to go with: if you've played No Thanks, they are the same kind of chips.
Things I think you should look for: an appropriate amount of heft, easy to pick up off the table, good size for how many you'll use. I think 23mm plastic is a good size and weight if you're going to use more than say 20 at a time or make a pile of them. For games with fewer pieces at a time, an unexplored estimation is that larger or heavier chips would make sense: plastic, clay, or wood - possibly closer to 3cm.
My parting piece of advice is that it's very important to get samples from the manufacturer before placing a large order. Typically the way this works is like a deposit against the final order: one sample is fairly expensive but the cost will be subtracted from the total amount you were originally quoted for the whole order. For me this came out to about $180. The purpose of the sample is to correct any errors the manufacturer made before you're stuck with the whole order of them. Assume they will make some.
I hope that helps! Feel free to ask me questions. Here's is a link to my game's page as well, if you'd like to hear more about that one specifically.