The "hearsay" answer is:
Xenarc is most expensive, but probably best quality. Possibly not as bright though, but I hear that they upgraded the screen to their upgrade brighter screen.
Lilliput has most of the dialogue lately, cheaper than the Xenarc, but it seems not as good quality, a pain to purchase, and probably a bigger pain to get serviced.
I think the jury is still out on the Starvision as everyone who has ordered one is still waiting for it (me too). Supposedly next week the USB touchscreen versions will be in and hopefully in the mail to me. So far this one is falling into the "pain to purchase" catagory too.
I don't know many that have had lots of experience with hands on experience with all the choices. The above is just a summary of posts that are as good as what they are.