The specific models listed here may not represent the latest versions in their particular lines, but they do represent exceptional value, as I understand it.
In any case, buy a used camera unless you have good reason to buy a new one. There are plenty of excellent cameras available used, often which already include a large memory card and extra battery. It seems preferable to simply recycle, but there are other good reasons to prefer older equipment.
Marketing departments must move merchandise, and more megapixels means more sales. The truth remains that these cameras have tiny sensors, and adding more pixels (without adding more area) necessarily increases noise and power consumption (don’t believe the hype). Fortunately, some (see Fuji F-series below) are finally breaking away from the pixel count race, and instead optimising for faster response (less noise) which means better pictures, especially in low light.
These cameras are roughly the size of a (thick) deck of playing cards. The vast majority of compact digital cameras have terribly slow sensors which give poor results in low light. The F30, F31fd, and F20 (all use the same sensor) remain unmatched; their low-light performance exceeds that of all other compact digital cameras (including, however strangely, even Fuji’s own later models in the same series).
Fuji was first to introduce, in compact cameras, sensors optimised for sensitivity rather than pixel count. One irritation is that most Fuji cameras (prior to 2007) use only xD-Picture Card (instead of the more common SD cards); however, they have finally begun supporting SD cards.
The F-series is confused: the F20, F40, F100fd are cheaper versions lacking shutter/aperture priority and other features. However, a more important distinction regards sensitivity (low light performance); the names of the low sensitivity cameras are struck through. Yes, the older cameras are more sensitive; however, the newer ones are still better than most other cameras in their class.
These are the smallest cameras which support (at minimum): RAW format, aperture/shutter priority, manual focus.
Before the LX1, these were the only compact cameras with RAW format (there were Fujis but their RAW format was somewhat cooked).