What's your favorite non-RPN HP?

[Joe Horn]

HP-71B, the only non-RPN HP calculator that I liked well enough to write a book about it. And for those who like RPN, the 71B could be turned into an RPN calculator the easy way (by installing the RPN program, a BIN file) or the hard way (by plugging in the 41 Translator ROM or the Forth ROM).