I have been using HP 42S for the past 15 years and would not replace it for any other. It is a pity that the LCD fades out in these and now it is only possible to see it at specific angles.
The device is reliable, the screen is amazing, the USB connectivity brings a lot of value and the community on SwissMicros' forum are passionate HP people.
I'm not affiliated with them in any way, just an happy geeky customer :)
Maybe I'll ask to be buried with them, so I can be dug up in a few thousand years and worry archeologists ;)