Which Pico model is best?

I recall at least a few people asking me questions about various Pico models in the past, so I suppose it'd be a good time to write this one down. :)

To start, there's a (probably still incomplete) list of Pico models, reivisons and editions over at Sega Retro.
While the sheer quantity of models seems high, there's one very important thing to note - With one notable exception, compatibility differences in most NTSC Pico models are few.
Japanese Pico games can boot on US Pico consoles without much hassle, and the inverse likewise. Their compatibility is one and the same.
Therefore, what would probably be the best solution would be to simply grab the cheapest Pico model you can. Most likely, this model will be a MK49325 Majesco US Pico. Of course, if you want, you can pay a bit more and get one of the multi-colored "Kids Communication Pico" Japanese models to have a more stand-out piece. I myself have a MK49002 Sega US Pico. The most common Japanese Pico systems available on eBay and Yahoo Japan Auctions appear to be Kids Communication Picos.

(Hey, look! Those Amazon listings on the right? There's a kinda-reasonable Pico right there!)

Whether your Pico models is from the USA or from Japan, it can pretty much play anything - except, that is, the StoryWare designed for the Mixt Book Player Copera.
This Japanese site has some good info on the Copera, including comparisons to standard Pico models.
Copera software, quite simply, will refuse to boot on a non-Copera model. The reasons are probably grounded in the hardware additions that the Copera has compared to the regular Pico model. Copera software also isn't emulated yet, sorry!

As I have never seen a Copera console for sale, I do not know what it'd potentially sell for, but the "exclusivity" factor will probably set it fairly high. Still, how much would you be willing to pay for compatibility with 10 more games?